Artykuły w czasopismach na temat „Hydroxylation”
Kliknij ten link, aby zobaczyć inne rodzaje publikacji na ten temat: Hydroxylation.
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 50 najlepszych artykułów w czasopismach naukowych na temat „Hydroxylation”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj artykuły w czasopismach z różnych dziedzin i twórz odpowiednie bibliografie.
1
Hilinski, Michael, Shea Johnson i Logan Combee. "Organocatalytic Atom-Transfer C(sp3)–H Oxidation". Synlett 29, nr 18 (27.06.2018): 2331–36. http://dx.doi.org/10.1055/s-0037-1610432.
Pełny tekst źródłaStreszczenie:
Predictably site-selective catalytic methods for intermolecular C(sp3)–H hydroxylation and amination hold great promise for the synthesis and late-stage modification of complex molecules. Transition-metal catalysis has been the most common approach for early investigations of this type of reaction. In comparison, there are far fewer reports of organocatalytic methods for direct oxygen or nitrogen insertion into C–H bonds. Herein, we provide an overview of early efforts in this area, with particular emphasis on our own recent development of an iminium salt that catalyzes both oxygen and nitrogen insertion.1 Introduction2 Background: C–H Oxidation Capabilities of Heterocyclic Oxidants3 Oxaziridine-Mediated Catalytic Hydroxylation4 Dioxirane-Mediated Catalytic Hydroxylation5 Iminium Salt Catalysis of Hydroxylation and Amination6 Conclusion and Outlook
2
Holland, Herbert L., Frances M. Brown, P. Chinna Chenchaiah i J. Appa Rao. "Hydroxylation of prostanoids by fungi. Synthesis of (−)-15-deoxy-19-(R)-hydroxy-PGE1 and (−)-15-deoxy-18-(S)-hydroxy-PGE1". Canadian Journal of Chemistry 68, nr 2 (1.02.1990): 282–93. http://dx.doi.org/10.1139/v90-039.
Pełny tekst źródłaStreszczenie:
A series of racemic substituted cyclopentanones, with alkyl groups corresponding to the upper prostanoid side chain and (or) the lower prostanoid side chain without the C-15 alcohol, has been synthesized. Using a steroid template for the prostanoid molecule as a basis for selection, fungi capable of hydroxylating steroids have been used to biotransform the prostanoid substrates. The predominant products were hydroxylated at the prostanoid C-18 and C-19 positions. The hydroxylations were enantioselective, with excesses in the range 10–60%, and in most cases the predominant configuration corresponded to that of the natural prostanoids. The stereochemistry of the C-19 hydroxyl group was found to be R by degradation of products to methyl 6-acetoxyheptanoate and comparison of that material with a resolved sample, obtained via crystallization of the brucine salt of ethyl 6-phthaloxyheptanoate. Hydroxylation at C-18 gave the S configuration of alcohol. Hydroxylation at prostanoid C-15 was observed, but in all cases this was accompanied by other reactions. Hydroxylation of Rhizopusarrhizus has been used in a preparation of (−)-15-deoxy-19-(R)-hydroxy-PGE1 and (−)-15-deoxy-18-(S)-hydroxy-PGE1. Keywords: biotransformation, hydroxylation, prostaglandins, prostanoids.
3
Masferrer-Rius, Eduard, Raoul M. Hopman, Jishai van der Kleij, Martin Lutz i Robertus J. M. Klein Gebbink. "On the Ability of Nickel Complexes Derived from Tripodal Aminopyridine Ligands to Catalyze Arene Hydroxylations". CHIMIA International Journal for Chemistry 74, nr 6 (24.06.2020): 489–94. http://dx.doi.org/10.2533/chimia.2020.489.
Pełny tekst źródłaStreszczenie:
The development of catalysts for the selective hydroxylation of aromatic C–H bonds is an essential challenge in current chemical research. The accomplishment of this goal requires the discovery of powerful metal-based oxidizing species capable of hydroxylating inert aromatic bonds in a selective manner, avoiding the generation of non-selective oxygen-centered radicals. Herein we show an investigation on the ability of nickel(ii) complexes supported by tripodal tetradentate aminopyridine ligands to catalyze the direct hydroxylation of benzene to phenol with H2O2 as oxidant. We have found that modifications on the ligand structure of the nickel complex do not translate into different reactivity, which differs from previous findings for nickel-based arene hydroxylations. Besides, several nickel(ii) salts have been found to be effective in the oxidation of aromatic C–H bonds. The use of fluorinated alcohols as solvent has been found to result in an increase in phenol yield; however, showing no more than two turn-overs per nickel. These findings raise questions on the nature of the oxidizing species responsible for the arene hydroxylation reaction.
4
Doostzadeh, J., i R. Morfin. "Effects of cytochrome P450 inhibitors and of steroid hormones on the formation of 7-hydroxylated metabolites of pregnenolone in mouse brain microsomes". Journal of Endocrinology 155, nr 2 (1.11.1997): 343–50. http://dx.doi.org/10.1677/joe.0.1550343.
Pełny tekst źródłaStreszczenie:
Hydroxylations of pregnenolone (PREG) at the 7 alpha- and 7 beta-positions have been reported in numerous murine tissues and organs and responsible cytochrome P450 (CYP) species await identification. Using thin layer chromatography and gas chromatography-mass spectrometry, we report identification of 7 alpha-hydroxy-PREG and 7 beta-hydroxy-PREG metabolites produced in mouse brain microsome digests and kinetic studies of their production with apparent KM values of 0.5 +/- 0.1 microM and 5.1 +/- 0.6 microM for 7 alpha- and 7 beta-hydroxylation respectively. Investigation of CYP inhibitors and of steroid hormone effects on both 7 alpha- and 7 beta-hydroxylations of PREG showed that: (i) different CYP were involved in 7 alpha- and 7 beta-hydroxylation of PREG because solely 7 alpha-hydroxylation was extensively inhibited by metyrapone, alpha-naphthoflavone, ketoconazole and 3 beta-hydroxysteroids, (ii) CYP 1A2, 2D6, 2B1 and 2B11 were not responsible for 7 alpha- and 7 beta-hydroxylation of PREG because respective specific inhibitors furafylline, quinidine and chloramphenicol triggered no inhibition, (iii) CYP 1A1 was responsible for only part of the 7 beta-hydroxylation of PREG because use of alpha-naphthoflavone, which inhibits specifically CYP 1A1, did not suppress entirely 7 beta-hydroxylation, while ketoconazole, metyrapone and antipyrine, which do not inhibit CYP 1A1, decreased part of the 7 beta-hydroxylation, (iv) 7 alpha-hydroxylation of PREG may be shared with other 3 beta-hydroxysteroids such as isoandrosterone and 5-androstene-3 beta,17 beta-diol which were strong inhibitors, but not with dehydroepiandrosterone which was a non-competitive inhibitor as weak as 3-oxosteroids, and (v) 7 beta-hydroxylation of PREG was not markedly changed by other steroids. Taken together, these findings will be of use for identification of the CYP species responsible for 7 alpha- and 7 beta-hydroxylation of PREG and for studies of their activities in brain.
5
Adams, J. S., i M. A. Gacad. "Characterization of 1 alpha-hydroxylation of vitamin D3 sterols by cultured alveolar macrophages from patients with sarcoidosis." Journal of Experimental Medicine 161, nr 4 (1.04.1985): 755–65. http://dx.doi.org/10.1084/jem.161.4.755.
Pełny tekst źródłaStreszczenie:
We investigated the 1 alpha-hydroxylation of vitamin D3 sterols by cultured pulmonary alveolar macrophages (PAM) from patients with sarcoidosis with or without clinically abnormal calcium homeostasis. Like the naturally occurring renal 1 alpha-hydroxylase, the PAM 1 alpha-hydroxylation reaction exhibited a high affinity for 25-hydroxyvitamin D3 (25-OH-D3) and a preference for substrates containing a 25-hydroxyl group in the side chain of the sterol. Unlike the renal enzyme, the PAM 1 alpha-hydroxylating mechanism was not accompanied by 24-hydroxylating activity, even after preincubation with 75 nM 1,25-dihydroxyvitamin D3 [1,25-(OH)2-D3] or exposure to high concentrations of substrate (500 nM 25-OH-D3). The PAM 25-OH-D3-1 alpha-hydroxylation reaction was stimulated by gamma interferon and inhibited by exposure to the glucocorticoid dexamethasone. The characteristics of the PAM hydroxylation process in vitro appear to reflect the efficiency of the extrarenal production of 1,25-(OH)2-D3 and the therapeutic efficacy of glucocorticoids in patients with sarcoidosis and disordered calcium metabolism.
6
Dahlbäck, H., i K. Wikvall. "25-Hydroxylation of vitamin D3 by a cytochrome P-450 from rabbit liver mitochondria". Biochemical Journal 252, nr 1 (15.05.1988): 207–13. http://dx.doi.org/10.1042/bj2520207.
Pełny tekst źródłaStreszczenie:
A cytochrome P-450 catalysing 25-hydroxylation of vitamin D3 was purified from liver mitochondria of untreated rabbits. The enzyme fraction contained 9 nmol of cytochrome P-450/mg of protein and showed only one protein band with an apparent Mr of 52,000 upon SDS/polyacrylamide-gel electrophoresis. The preparation showed a single protein spot with an apparent isoelectric point of 7.8 and an Mr of approx. 52,000 upon two-dimensional isoelectric-focusing-polyacrylamide-gel electrophoresis. The purified cytochrome P-450 catalysed 25-hydroxylation of vitamin D3 up to 5000 times more efficiently than did the mitochondria. The cytochrome P-450 required both ferredoxin and ferredoxin reductase for catalytic activity. Microsomal NADPH-cytochrome P-450 reductase could not replace ferredoxin and ferredoxin reductase. The cytochrome P-450 catalysed, in addition to 25-hydroxylation of vitamin D3, the 25-hydroxylation of 1 alpha-hydroxyvitamin D3 and the 26-hydroxylation of 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha-triol. The enzyme did not catalyse side-chain cleavage of cholesterol, 11 beta-hydroxylation of deoxycorticosterone, 1 alpha-hydroxylation of 25-hydroxyvitamin D3, hydroxylations of lauric acid and testosterone or demethylation of benzphetamine. The results raise the possibility that the 25-hydroxylation of vitamin D3 and the 26-hydroxylation of C27 steroids are catalysed by the same species of cytochrome P-450 in liver mitochondria. The possible role of the liver mitochondrial cytochrome P-450 in the metabolism of vitamin D3 is discussed.
7
Ramirez, Leyla C., i Bernard F. Maume. "Regulation of 11β/18-steroid hydroxylation in newborn rat adrenal cells in primary culture". Acta Endocrinologica 111, nr 1 (styczeń 1986): 106–15. http://dx.doi.org/10.1530/acta.0.1110106.
Pełny tekst źródłaStreszczenie:
Abstract. In newborn rat adrenal cells in primary culture, the level of activity of the 11β/18-steroid hydroxylase system involved in the last step of the corticosteroid biosynthesis is increased by ACTH. A parallel study of 11β- and 18-hydroxylation showed the same apparent Km values (64 μm) for both hydroxylations. The Vmax values differed: 11.5 μg/106 cells/h for corticosterone and 6.9 μg/106 cells/h for 18-hydroxyDOC. A dose response study of the ACTH effect, measured by the bioconversion of deoxycorticosterone to corticosterone and 18-hydroxyDOC, showed maximum hydroxylation with a dose of 2.2 mU of ACTH/ml. Addition of ACTH after several weeks in culture produced a smaller increase in 1 1β/18-hydroxylation. Removal of ACTH after several weeks of treatment produced an immediate decrease in corticosteroid production; readdition of ACTH produced an increase to the previous level in the case of the 22 mU/ml dose, but not in the case of the 2.2 mU/ml dose. The use of actinomycin D demonstrated that ACTH affects mainly the biosynthesis of protein which must be renewed approximately every 24 h. Finally, the effect of pretreatment or co-treatment with various concentrations of the end products of the reaction showed no inhibition or destruction of the I 1β/18-hydroxylating enzyme system. Therefore, the regulation of the 11β/18-steroid hydroxylase system in these cell cultures seems to be accomplished through the induction by ACTH of the transcription involved in the biosynthesis of cytochrome P45011β and the amount of available precursor furnished by endogenous steroidogenesis.
8
Veronese, M. E., C. J. Doecke, P. I. Mackenzie, M. E. McManus, J. O. Miners, D. L. Rees, R. Gasser, U. A. Meyer i D. J. Birkett. "Site-directed mutation studies of human liver cytochrome P-450 isoenzymes in the CYP2C subfamily". Biochemical Journal 289, nr 2 (15.01.1993): 533–38. http://dx.doi.org/10.1042/bj2890533.
Pełny tekst źródłaStreszczenie:
Evidence from human studies in vivo and in vitro strongly suggests that the methylhydroxylation of tolbutamide and the 4-hydroxylation of phenytoin, the major pathways in the elimination of these two drugs, are catalysed by the same cytochrome P-450 isoenzyme(s). In the present study we used site-directed mutagenesis and cDNA expression in COS cells to characterize in detail the kinetics of tolbutamide and phenytoin hydroxylations by seven CYP2C proteins (2C8, 2C9 and variants, and 2C10) in order to define the effects of small changes in amino acid sequences and the likely proteins responsible in the metabolism of these two drugs in man. Tolbutamide was hydroxylated to varying extents by all expressed cytochrome P-450 isoenzymes, although activity was much lower for the expressed 2C8 protein. While the apparent Km values for the 2C9/10 isoenzymes (71.6-131.7 microM) were comparable with the range of apparent Km values previously observed in human liver microsomes, the apparent Km for 2C8 (650.5 microM) was appreciably higher. The 2C8 enzyme also showed quite different sulphaphenazole inhibition characteristics. The 4-hydroxylation of phenytoin was also more efficiently catalysed by the 2C9/10 enzymes. These enzymes showed similarities in kinetics of phenytoin hydroxylation and sulphaphenazole inhibition compared with human liver phenytoin hydroxylase. Also of interest was the observation that, among the 2C9 variants, small differences in amino acid composition could appreciably affect both tolbutamide and phenytoin hydroxylations. The amino acid substitution Cys-144->Arg increased both the rates of tolbutamide and phenytoin hydroxylations, while the Leu-359->Ile change had a greater effect on phenytoin hydroxylation. We conclude that: (1) although 2C8 and 2C9/10 proteins metabolize tolbutamide. only 2C9/10 proteins play a major role in human liver; (2) 2C9/10 proteins also appear to be chiefly responsible for phenytoin hydroxylation; and (3) subtle differences in the amino acid composition of these 2C9/10 proteins can affect the functional specificities towards both tolbutamide and phenytoin.
9
Axén, E., T. Bergman i K. Wikvall. "Purification and characterization of a vitamin D3 25-hydroxylase from pig liver microsomes". Biochemical Journal 287, nr 3 (1.11.1992): 725–31. http://dx.doi.org/10.1042/bj2870725.
Pełny tekst źródłaStreszczenie:
A cytochrome P-450 which catalyses 25-hydroxylation of vitamin D3 has been purified to apparent homogeneity from pig liver microsomes. The specific content of cytochrome P-450 was 12 nmol.mg of protein-1, and the preparation showed a single band with an apparent M(r) of 50,500 upon SDS/PAGE. A monoclonal antibody raised against the vitamin D3 25-hydroxylase reacted strongly with the purified 25-hydroxylating cytochrome P-450 from pig kidney microsomes [Bergman & Postlind (1990) Biochem. J. 270, 345-350]. The liver enzyme showed structural and functional properties very similar to those of the kidney enzyme. The two enzymes differed with respect to only one of the first 16 N-terminal amino acids. The vitamin D3 25-hydroxylase in pig liver microsomes exhibited a turnover and an apparent Km for 25-hydroxylation of vitamin D3 which were of the same order of magnitude as those of a well-characterized male-specific 25-hydroxylating cytochrome P-450 in rat liver microsomes. The two enzymes differed structurally. The pig liver enzyme was, in contrast to the rat liver enzyme, not sex-specific, and did not catalyse 16 alpha-hydroxylation of testosterone. These properties of the 25-hydroxylase in rat liver microsomes have led to questions on the role of microsomal 25-hydroxylation of vitamin D3. It is concluded that studies on microsomal 25-hydroxylation with the rat may be misleading. The results of the present study show that the pig appears to be a representative species for evaluation of vitamin D3 hydroxylases in other mammals, including man.
10
Webb, James D., Andrea Murányi, Christopher W. Pugh, Peter J. Ratcliffe i Mathew L. Coleman. "MYPT1, the targeting subunit of smooth-muscle myosin phosphatase, is a substrate for the asparaginyl hydroxylase factor inhibiting hypoxia-inducible factor (FIH)". Biochemical Journal 420, nr 2 (13.05.2009): 327–36. http://dx.doi.org/10.1042/bj20081905.
Pełny tekst źródłaStreszczenie:
The asparaginyl hydroxylase FIH [factor inhibiting HIF (hypoxia-inducible factor)] was first identified as a protein that inhibits transcriptional activation by HIF, through hydroxylation of an asparagine residue in the CAD (C-terminal activation domain). More recently, several ARD [AR (ankyrin repeat) domain]-containing proteins were identified as FIH substrates using FIH interaction assays. Although the function(s) of these ARD hydroxylations is unclear, expression of the ARD protein Notch1 was shown to compete efficiently with HIF CAD for asparagine hydroxylation and thus to enhance HIF activity. The ARD is a common protein domain with over 300 examples in the human proteome. However, the extent of hydroxylation among ARD proteins, and the ability of other members to compete with HIF–CAD for FIH, is not known. In the present study we assay for asparagine hydroxylation in a bioinformatically predicted FIH substrate, the targeting subunit of myosin phosphatase, MYPT1. Our results confirm hydroxylation both in cultured cells and in endogenous protein purified from animal tissue. We show that the extent of hydroxylation at three sites is dependent on FIH expression level and that hydroxylation is incomplete under basal conditions even in the animal tissue. We also show that expression of MYPT1 enhances HIF–CAD activity in a manner consistent with competition for FIH and that this property extends to other ARD proteins. These results extend the range of FIH substrates and suggest that cross-competition between ARDs and HIF–CAD, and between ARDs themselves, may be extensive and have important effects on hypoxia signalling.
11
Zimniak, P., E. J. Holsztynska, A. Radominska, M. Iscan, R. Lester i D. J. Waxman. "Distinct forms of cytochrome P-450 are responsible for 6β-hydroxylation of bile acids and of neutral steroids". Biochemical Journal 275, nr 1 (1.04.1991): 105–11. http://dx.doi.org/10.1042/bj2750105.
Pełny tekst źródłaStreszczenie:
Cytochrome P-450-dependent 6 beta-hydroxylation of bile acids in rat liver contributes to the synthesis of the quantitatively important pool of 6-hydroxylated bile acids, as well as to the detoxification of hydrophobic bile acids. The lithocholic acid 6 beta-hydroxylation reaction was investigated and compared with androstenedione 6 beta-hydroxylation. Differential responses of these two activities to inducers and inhibitors of microsomal P-450 enzymes, lack of mutual inhibition by the two substrates and differential inhibition by antibodies raised against several purified hepatic cytochromes P-450 were observed. From these results it was concluded that 6 beta-hydroxylation of lithocholic acid is catalysed by P-450 form(s) different from the subfamily IIIA cytochromes P-450 which are responsible for the bulk of microsomal androstenedione 6 beta-hydroxylation. Similar, but more tentative, results revealed that the 7 alpha-hydroxylation of lithocholic acid and of androstenedione may be also catalysed by distinct P-450 enzymes. The results indicate that cytochromes P-450 hydroxylating bile acids are distinct from analogous enzymes that carry out reactions of the same regio- and stereo-specificity on neutral steroids (steroid hormones). A comparison of pairs of cytochromes P-450 that catalyse the same reaction on closely related steroid molecules will help to define those structural elements in the proteins that determine the recognition of their respective substrates.
12
Lo Sciuto, Alessandra, Matteo Cervoni, Roberta Stefanelli, Maria Concetta Spinnato, Alessandra Di Giamberardino, Carmine Mancone i Francesco Imperi. "Genetic Basis and Physiological Effects of Lipid A Hydroxylation in Pseudomonas aeruginosa PAO1". Pathogens 8, nr 4 (10.12.2019): 291. http://dx.doi.org/10.3390/pathogens8040291.
Pełny tekst źródłaStreszczenie:
Modifications of the lipid A moiety of lipopolysaccharide influence the physicochemical properties of the outer membrane of Gram-negative bacteria. Some bacteria produce lipid A with a single hydroxylated secondary acyl chain. This hydroxylation is catalyzed by the dioxygenase LpxO, and is important for resistance to cationic antimicrobial peptides (e.g., polymyxins), survival in human blood, and pathogenicity in animal models. The lipid A of the human pathogen Pseudomonas aeruginosa can be hydroxylated in both secondary acyl chains, but the genetic basis and physiological role of these hydroxylations are still unknown. Through the generation of single and double deletion mutants in the lpxO1 and lpxO2 homologs of P. aeruginosa PAO1 and lipid A analysis by mass spectrometry, we demonstrate that both LpxO1 and LpxO2 are responsible for lipid A hydroxylation, likely acting on different secondary acyl chains. Lipid A hydroxylation does not appear to affect in vitro growth, cell wall stability, and resistance to human blood or antibiotics in P. aeruginosa. In contrast, it is required for infectivity in the Galleria mellonella infection model, without relevantly affecting in vivo persistence. Overall, these findings suggest a role for lipid A hydroxylation in P. aeruginosa virulence that could not be directly related to outer membrane integrity.
13
Mukuria, C. J., W. D. Mwangi, A. Noguchi, G. P. Waiyaki, T. Asano i M. Naiki. "Evidence for a free N-acetylneuraminic acid-hydroxylating enzyme in pig mandibular gland soluble fraction". Biochemical Journal 305, nr 2 (15.01.1995): 459–64. http://dx.doi.org/10.1042/bj3050459.
Pełny tekst źródłaStreszczenie:
The activity of a free N-acetylneuraminic acid (Neu5Ac)-hydroxylating enzyme which converted Neu5Ac into N-glycolyl-neuraminic acid (Neu5Gc) was demonstrated in the soluble fraction of pig mandibular gland. The hydroxylation was possible only with NADPH as the electron donor. The apparent Km was 4.5 mM Neu5Ac. At 0.5 mM monovalent cations had no effect on the hydroxylation of Neu5Ac whereas bivalent cations gave varied inhibition capacities ranging from 14 to 75%. EDTA gave a time-dependent enhancement of activity. It was concluded that the enzyme does not require an exogenously added inorganic cofactor. Results from salt fractionation of the soluble fraction and the use of inhibitors such as mercurials suggested that the hydroxylation of Neu5Ac to Neu5Gc may involve other, as yet unknown, component(s) and the possibility of electrons donated by NADPH being transferred to activated molecular oxygen (second substrate). We propose to name this enzyme N-acetyl-neuraminic acid hydroxylase.
14
Court, Michael H., Su X. Duan, Leah M. Hesse, Karthik Venkatakrishnan i David J. Greenblatt. "Cytochrome P-450 2B6 Is Responsible for Interindividual Variability of Propofol Hydroxylation by Human Liver Microsomes". Anesthesiology 94, nr 1 (1.01.2001): 110–19. http://dx.doi.org/10.1097/00000542-200101000-00021.
Pełny tekst źródłaStreszczenie:
Background Oxidation of propofol to 4-hydroxypropofol represents a significant pathway in the metabolism of this anesthetic agent in humans. The aim of this study was to identify the principal cytochrome P-450 (CYP) isoforms mediating this biotransformation. Methods Propofol hydroxylation activities and enzyme kinetics were determined using human liver microsomes and cDNA-expressed CYPs. CYP-specific marker activities and CYP2B6 protein content were also quantified in hepatic microsomes for correlational analyses. Finally, inhibitory antibodies were used to ascertain the relative contribution of CYPs to propofol hydroxylation by hepatic microsomes. Results Propofol hydroxylation by hepatic microsomes showed more than 19-fold variability and was most closely correlated to CYP2B6 protein content (r = 0.904), and the CYP2B6 marker activities, S-mephenytoin N-demethylation (r = 0.919) and bupropion hydroxylation (r = 0.854). High- and intermediate-activity livers demonstrated high-affinity enzyme kinetics (K(m) < 8 microm), whereas low-activity livers displayed low-affinity kinetics (K(m) > 80 microm). All of the CYPs evaluated were capable of hydroxylating propofol; however, CYP2B6 and CYP2C9 were most active. Kinetic analysis indicated that CYP2B6 is a high-affinity (K(m) = 10 +/- 2 microm; mean +/- SE of the estimate), high-capacity enzyme, whereas CYP2C9 is a low-affinity (K(m) = 41 +/- 8 microm), high-capacity enzyme. Furthermore, immunoinhibition showed a greater contribution of CYP2B6 (56 +/- 22% inhibition; mean +/- SD) compared with CYP2C isoforms (16 +/- 7% inhibition) to hepatic microsomal activity. Conclusions Cytochrome P-450 2B6, and to a lesser extent CYP2C9, contribute to the oxidative metabolism of propofol. However, CYP2B6 is the principal determinant of interindividual variability in the hydroxylation of this drug by human liver microsomes.
15
Bergman, T., i H. Postlind. "Characterization of mitochondrial cytochromes P-450 from pig kidney and liver catalysing 26-hydroxylation of 25-hydroxyvitamin D3 and C27 steroids". Biochemical Journal 276, nr 2 (1.06.1991): 427–32. http://dx.doi.org/10.1042/bj2760427.
Pełny tekst źródłaStreszczenie:
The properties of cytochrome P-450 from pig kidney mitochondria, catalysing 26-hydroxylation of 25-hydroxyvitamin D3 and C27 steroids [Postlind & Wikvall (1989) Biochem. Biophys. Res. Commun. 159, 1135-1140; Postlind (1990) Biochem. Biophys. Res. Commun. 168, 261-266], were compared with those of a 26-hydroxylating cytochrome P-450 from pig liver mitochondria. The liver enzyme was purified to a cytochrome P-450 content of 7.4 nmol/mg of protein and showed only one protein band with an apparent Mr of 53,000 upon SDS/PAGE. The cytochrome P-450 catalysed 26-hydroxylation of 25-hydroxyvitamin D3, cholesterol and 5 beta-cholestane-3 alpha, 7 alpha-diol at rates of 361, 1090 and 2065 pmol/min per nmol of cytochrome P-450. A monoclonal antibody against the purified liver mitochondrial cytochrome P-450 26-hydroxylase (cytochrome P-450(26] was prepared. After coupling to Sepharose, the antibody was able to bind to cytochrome P-450(26) from liver as well as from kidney mitochondria and to immunoprecipitate the 26-hydroxylase activity towards 25-hydroxyvitamin D3 and cholesterol when assayed in a reconstituted system. After SDS/PAGE and immunoblotting with the antibody, the cytochrome P-450(26) was detected in the purified liver and kidney preparations. These results indicate that similar species of cytochrome P-450 catalyse 26-hydroxylation of 25-hydroxyvitamin D3 and C27 steroids in liver and kidney mitochondria. The results with the monoclonal antibody together with the finding that cholesterol competitively inhibits the 26-hydroxylation of 25-hydroxyvitamin D3 further indicate that 26-hydroxylation of 25-hydroxyvitamin D3 and cholesterol is catalysed by the same species of cytochrome P-450 in each tissue. The N-terminal amino acid sequence of cytochrome P-450(26) in kidney mitochondria resembled that of pig kidney microsomal 25-hydroxylase active in 25-hydroxylation of vitamin D3 and C27 steroids, whereas the sequence of pig liver mitochondrial cytochrome P-450(26) differed from those of rabbit and rat liver mitochondrial 26-hydroxylases as well as from those of other hitherto isolated mammalian cytochromes P-450.
16
Bergman, T., i H. Postlind. "Characterization of pig kidney microsomal cytochrome P-450 catalysing 25-hydroxylation of vitamin D3 and C27 steroids". Biochemical Journal 270, nr 2 (1.09.1990): 345–50. http://dx.doi.org/10.1042/bj2700345.
Pełny tekst źródłaStreszczenie:
The cytochrome P-450 enzyme which catalyses 25-hydroxylation of vitamin D3 (cytochrome P-450(25] from pig kidney microsomes [Postlind & Wikvall (1988) Biochem. J. 253, 549-552] has been further purified. The specific content of cytochrome P-450 was 15.0 nmol.mg of protein-1, and the protein showed a single spot with an apparent isoelectric point of 7.4 and an Mr of 50,500 upon two-dimensional isoelectric-focusing/SDS/PAGE. The 25-hydroxylase activity towards vitamin D3 was 124 pmol.min-1.nmol of cytochrome P-450-1 and towards 1 alpha-hydroxyvitamin D3 it was 1375 pmol.min-1.nmol-1. The preparation also catalysed the 25-hydroxylation of 5 beta-cholestane-3 alpha,7 alpha-diol at a rate of 1000 pmol.min-1.nmol of cytochrome P-450-1 and omega-1 hydroxylation of lauric acid at a rate of 200 pmol.min-1.nmol of cytochrome P-450-1. A monoclonal antibody raised against the 25-hydroxylating cytochrome P-450, designated mAb 25E5, was prepared. After coupling to Sepharose, the antibody was able to bind to cytochrome P-450(25) from kidney as well as from pig liver microsomes, and to immunoprecipitate the activity for 25-hydroxylation of vitamin D3 and 5 beta-cholestane-3 alpha,7 alpha-diol when assayed in a reconstituted system. The hydroxylase activity towards lauric acid was not inhibited by the antibody. By SDS/PAGE and immunoblotting with mAb 25E5, cytochrome P-450(25) was detected in both pig kidney and pig liver microsomes. These results indicate a similar or the same species of cytochrome P-450 in pig kidney and liver microsomes catalysing 25-hydroxylation of vitamin D3 and C27 steroids. The N-terminal amino acid sequence of the purified cytochrome P-450(25) from pig kidney microsomes differed from those of hitherto isolated mammalian cytochromes P-450.
17
Küpfer, A., i R. A. Branch. "Stereoselective mephobarbital hydroxylation cosegregates with mephenytoin hydroxylation". Clinical Pharmacology and Therapeutics 38, nr 4 (październik 1985): 414–18. http://dx.doi.org/10.1038/clpt.1985.196.
Pełny tekst źródła
18
Crosby, Samantha V., Izzeldin Y. Ahmed, Laura R. Osborn, Zeyuan Wang, Mary A. Schleiff, William E. Fantegrossi, Swati Nagar, Paul L. Prather, Gunnar Boysen i Grover P. Miller. "Similar 5F-APINACA Metabolism between CD-1 Mouse and Human Liver Microsomes Involves Different P450 Cytochromes". Metabolites 12, nr 8 (22.08.2022): 773. http://dx.doi.org/10.3390/metabo12080773.
Pełny tekst źródłaStreszczenie:
In 2019, synthetic cannabinoids accounted for more than one-third of new drugs of abuse worldwide; however, assessment of associated health risks is not ethical for controlled and often illegal substances, making CD-1 mouse exposure studies the gold standard. Interpretation of those findings then depends on the similarity of mouse and human metabolic pathways. Herein, we report the first comparative analysis of steady-state metabolism of N-(1-adamantyl)-1-(5-pentyl)-1H-indazole-3-carboxamide (5F-APINACA/5F-AKB48) in CD-1 mice and humans using hepatic microsomes. Regardless of species, 5F-APINACA metabolism involved highly efficient sequential adamantyl hydroxylation and oxidative defluorination pathways that competed equally. Secondary adamantyl hydroxylation was less efficient for mice. At low 5F-APINACA concentrations, initial rates were comparable between pathways, but at higher concentrations, adamantyl hydroxylations became less significant due to substrate inhibition likely involving an effector site. For humans, CYP3A4 dominated both metabolic pathways with minor contributions from CYP2C8, 2C19, and 2D6. For CD-1 mice, Cyp3a11 and Cyp2c37, Cyp2c50, and Cyp2c54 contributed equally to adamantyl hydroxylation, but Cyp3a11 was more efficient at oxidative defluorination than Cyp2c members. Taken together, the results of our in vitro steady-state study indicate a high conservation of 5F-APINACA metabolism between CD-1 mice and humans, but deviations can occur due to differences in P450s responsible for the associated reactions.
19
Hu, Xuan-Bo, Qian-Qian Fu, Xue-Ying Huang, Xue-Qiang Chu, Zhi-Liang Shen, Chengping Miao i Weiyi Chen. "Hydroxylation of Aryl Sulfonium Salts for Phenol Synthesis under Mild Reaction Conditions". Molecules 29, nr 4 (13.02.2024): 831. http://dx.doi.org/10.3390/molecules29040831.
Pełny tekst źródłaStreszczenie:
Hydroxylation of aryl sulfonium salts could be realized by utilizing acetohydroxamic acid and oxime as hydroxylative agents in the presence of cesium carbonate as a base, leading to a variety of structurally diverse hydroxylated arenes in 47–95% yields. In addition, the reaction exhibited broad functionality tolerance, and a range of important functional groups (e.g., cyano, nitro, sulfonyl, formyl, keto, and ester) could be well amenable to the mild reaction conditions.
20
Fan, Tengjiao, Guohui Sun, Lijiao Zhao, Xin Cui i Rugang Zhong. "Metabolic Activation and Carcinogenesis of Tobacco-Specific Nitrosamine N’-Nitrosonornicotine (NNN): A Density Function Theory and Molecular Docking Study". International Journal of Environmental Research and Public Health 16, nr 2 (9.01.2019): 178. http://dx.doi.org/10.3390/ijerph16020178.
Pełny tekst źródłaStreszczenie:
N’-nitrosonornicotine (NNN) is one of the tobacco-specific nitrosamines (TSNAs) that exists widely in smoke and smokeless tobacco products. NNN can induce tumors in various laboratory animal models and has been identified by International Agency for Research on Cancer (IARC) as a human carcinogen. Metabolic activation of NNN is primarily initiated by cytochrome P450 enzymes (CYP450s) via 2′-hydroxylation or 5′-hydroxylation. Subsequently, the hydroxylating intermediates undergo spontaneous decomposition to generate diazohydroxides, which can be further converted to alkyldiazonium ions, followed by attacking DNA to form various DNA damages, such as pyridyloxobutyl (POB)-DNA adducts and pyridyl-N-pyrrolidinyl (py-py)-DNA adducts. If not repaired correctly, these lesions would lead to tumor formation. In the present study, we performed density functional theory (DFT) computations and molecular docking studies to understand the mechanism of metabolic activation and carcinogenesis of NNN. DFT calculations were performed to explore the 2′- or 5′- hydroxylation reaction of (R)-NNN and (S)-NNN. The results indicated that NNN catalyzed by the ferric porphyrin (Compound I, Cpd I) at the active center of CYP450 included two steps, hydrogen abstraction and rebound reactions. The free energy barriers of the 2′- and 5′-hydroxylation of NNN are 9.82/8.44 kcal/mol (R/S) and 7.99/9.19 kcal/mol (R/S), respectively, suggesting that the 2′-(S) and 5′-(R) pathways have a slight advantage. The free energy barriers of the decomposition occurred at the 2′-position and 5′-position of NNN are 18.04/18.02 kcal/mol (R/S) and 18.33/19.53 kcal/mol (R/S), respectively. Moreover, we calculated the alkylation reactions occurred at ten DNA base sites induced by the 2′-hydroxylation product of NNN, generating the free energy barriers ranging from 0.86 to 4.72 kcal/mol, which indicated that these reactions occurred easily. The docking study showed that (S)-NNN had better affinity with CYP450s than that of (R)-NNN, which was consistent with the experimental results. Overall, the combined results of the DFT calculations and the docking obtained in this study provide an insight into the understanding of the carcinogenesis of NNN and other TSNAs.
21
Hibi, Makoto, Ryosuke Mori, Ryoma Miyake, Hiroshi Kawabata, Shoko Kozono, Satomi Takahashi i Jun Ogawa. "Novel Enzyme Family Found in Filamentous Fungi Catalyzingtrans-4-Hydroxylation of l-Pipecolic Acid". Applied and Environmental Microbiology 82, nr 7 (22.01.2016): 2070–77. http://dx.doi.org/10.1128/aem.03764-15.
Pełny tekst źródłaStreszczenie:
ABSTRACTHydroxypipecolic acids are bioactive compounds widely distributed in nature and are valuable building blocks for the organic synthesis of pharmaceuticals. We have found a novel hydroxylating enzyme with activity towardl-pipecolic acid (l-Pip) in a filamentous fungus,Fusarium oxysporumc8D. The enzymel-Piptrans-4-hydroxylase (Pip4H) ofF. oxysporum(FoPip4H) belongs to the Fe(II)/α-ketoglutarate-dependent dioxygenase superfamily, catalyzes the regio- and stereoselective hydroxylation ofl-Pip, and produces optically puretrans-4-hydroxy-l-pipecolic acid (trans-4-l-HyPip). Amino acid sequence analysis revealed several fungal enzymes homologous withFoPip4H, and five of these also hadl-Piptrans-4-hydroxylation activity. In particular, the homologous Pip4H enzyme derived fromAspergillus nidulansFGSC A4 (AnPip4H) had a broader substrate specificity spectrum than other homologues and reacted with thelanddforms of various cyclic and aliphatic amino acids. UsingFoPip4H as a biocatalyst, a system for the preparative-scale production of chiraltrans-4-l-HyPip was successfully developed. Thus, we report a fungal family ofl-Pip hydroxylases and the enzymatic preparation oftrans-4-l-HyPip, a bioactive compound and a constituent of secondary metabolites with useful physiological activities.
22
Knack, Daniel, Corina Hagel, Maciej Szaleniec, Agnieszka Dudzik, Aleksander Salwinski i Johann Heider. "Substrate and Inhibitor Spectra of Ethylbenzene Dehydrogenase: Perspectives on Application Potential and Catalytic Mechanism". Applied and Environmental Microbiology 78, nr 18 (6.07.2012): 6475–82. http://dx.doi.org/10.1128/aem.01551-12.
Pełny tekst źródłaStreszczenie:
ABSTRACTEthylbenzene dehydrogenase (EbDH) catalyzes the initial step in anaerobic degradation of ethylbenzene in denitrifying bacteria, namely, the oxygen-independent hydroxylation of ethylbenzene to (S)-1-phenylethanol. In our study we investigate the kinetic properties of 46 substrate analogs acting as substrates or inhibitors of the enzyme. The apparent kinetic parameters of these compounds give important insights into the function of the enzyme and are consistent with the predicted catalytic mechanism based on a quantum chemical calculation model. In particular, the existence of the proposed substrate-derived radical and carbocation intermediates is substantiated by the formation of alternative dehydrogenated and hydroxylated products from some substrates, which can be regarded as mechanistic models. In addition, these results also show the surprisingly high diversity of EbDH in hydroxylating different kinds of alkylaromatic and heterocyclic compounds to the respective alcohols. This may lead to attractive industrial applications of ethylbenzene dehydrogenase for a new process of producing alcohols via hydroxylation of the corresponding aromatic hydrocarbons rather than the customary procedure of reducing the corresponding ketones.
23
Spina, Edoardo, Eugen Steiner, Örjan Ericsson i Folke Sjöqvist. "Hydroxylation of desmethylimipramine: Dependence on the debrisoquin hydroxylation phenotype". Clinical Pharmacology and Therapeutics 41, nr 3 (marzec 1987): 314–19. http://dx.doi.org/10.1038/clpt.1987.33.
Pełny tekst źródła
24
Jóźwik, Ilona K., Martin Litzenburger, Yogan Khatri, Alexander Schifrin, Marco Girhard, Vlada Urlacher, Andy-Mark W. H. Thunnissen i Rita Bernhardt. "Structural insights into oxidation of medium-chain fatty acids and flavanone by myxobacterial cytochrome P450 CYP267B1". Biochemical Journal 475, nr 17 (11.09.2018): 2801–17. http://dx.doi.org/10.1042/bcj20180402.
Pełny tekst źródłaStreszczenie:
Oxidative biocatalytic reactions performed by cytochrome P450 enzymes (P450s) are of high interest for the chemical and pharmaceutical industries. CYP267B1 is a P450 enzyme from myxobacterium Sorangium cellulosum So ce56 displaying a broad substrate scope. In this work, a search for new substrates was performed, combined with product characterization and a structural analysis of substrate-bound complexes using X-ray crystallography and computational docking. The results demonstrate the ability of CYP267B1 to perform in-chain hydroxylations of medium-chain saturated fatty acids (decanoic acid, dodecanoic acid and tetradecanoic acid) and a regioselective hydroxylation of flavanone. The fatty acids are mono-hydroxylated at different in-chain positions, with decanoic acid displaying the highest regioselectivity towards ω-3 hydroxylation. Flavanone is preferably oxidized to 3-hydroxyflavanone. High-resolution crystal structures of CYP267B1 revealed a very spacious active site pocket, similarly to other P450s capable of converting macrocyclic compounds. The pocket becomes more constricted near to the heme and is closed off from solvent by residues of the F and G helices and the B–C loop. The crystal structure of the tetradecanoic acid-bound complex displays the fatty acid bound near to the heme, but in a nonproductive conformation. Molecular docking allowed modeling of the productive binding modes for the four investigated fatty acids and flavanone, as well as of two substrates identified in a previous study (diclofenac and ibuprofen), explaining the observed product profiles. The obtained structures of CYP267B1 thus serve as a valuable prediction tool for substrate hydroxylations by this highly versatile enzyme and will encourage future selectivity changes by rational protein engineering.
25
Kim, Dockyu, Miyoun Yoo, Ki Young Choi, Beom Sik Kang, Tai Kyoung Kim, Soon Gyu Hong, Gerben J. Zylstra i Eungbin Kim. "Differential Degradation of Bicyclics with Aromatic and Alicyclic Rings by Rhodococcus sp. Strain DK17". Applied and Environmental Microbiology 77, nr 23 (30.09.2011): 8280–87. http://dx.doi.org/10.1128/aem.06359-11.
Pełny tekst źródłaStreszczenie:
ABSTRACTThe metabolically versatileRhodococcussp. strain DK17 is able to grow on tetralin and indan but cannot use their respective desaturated counterparts, 1,2-dihydronaphthalene and indene, as sole carbon and energy sources. Metabolite analyses by gas chromatography-mass spectrometry and nuclear magnetic resonance spectrometry clearly show that (i) themeta-cleavage dioxygenase mutant strain DK180 accumulates 5,6,7,8-tetrahydro-1,2-naphthalene diol, 1,2-indene diol, and 3,4-dihydro-naphthalene-1,2-diol from tetralin, indene, and 1,2-dihydronaphthalene, respectively, and (ii) when expressed inEscherichia coli, the DK17o-xylene dioxygenase transforms tetralin, indene, and 1,2-dihydronaphthalene into tetralincis-dihydrodiol, indan-1,2-diol, andcis-1,2-dihydroxy-1,2,3,4-tetrahydronaphthalene, respectively. Tetralin, which is activated by aromatic hydroxylation, is degraded successfully via the ring cleavage pathway to support growth of DK17. Indene and 1,2-dihydronaphthalene do not serve as growth substrates because DK17 hydroxylates them on the alicyclic ring and further metabolism results in a dead-end metabolite. This study reveals that aromatic hydroxylation is a prerequisite for proper degradation of bicyclics with aromatic and alicyclic rings by DK17 and confirms the unique ability of the DK17o-xylene dioxygenase to perform distinct regioselective hydroxylations.
26
Markolovic, Suzana, Sarah E. Wilkins i Christopher J. Schofield. "Protein Hydroxylation Catalyzed by 2-Oxoglutarate-dependent Oxygenases". Journal of Biological Chemistry 290, nr 34 (7.07.2015): 20712–22. http://dx.doi.org/10.1074/jbc.r115.662627.
Pełny tekst źródłaStreszczenie:
The post-translational hydroxylation of prolyl and lysyl residues, as catalyzed by 2-oxoglutarate (2OG)-dependent oxygenases, was first identified in collagen biosynthesis. 2OG oxygenases also catalyze prolyl and asparaginyl hydroxylation of the hypoxia-inducible factors that play important roles in the adaptive response to hypoxia. Subsequently, they have been shown to catalyze N-demethylation (via hydroxylation) of Nϵ-methylated histone lysyl residues, as well as hydroxylation of multiple other residues. Recent work has identified roles for 2OG oxygenases in the modification of translation-associated proteins, which in some cases appears to be conserved from microorganisms through to humans. Here we give an overview of protein hydroxylation catalyzed by 2OG oxygenases, focusing on recent discoveries.
27
Flashman, Emily, Sarah L. Davies, Kar Kheng Yeoh i Christopher J. Schofield. "Investigating the dependence of the hypoxia-inducible factor hydroxylases (factor inhibiting HIF and prolyl hydroxylase domain 2) on ascorbate and other reducing agents". Biochemical Journal 427, nr 1 (15.03.2010): 135–42. http://dx.doi.org/10.1042/bj20091609.
Pełny tekst źródłaStreszczenie:
The HIF (hypoxia-inducible factor) hydroxylases [PHDs or EGLNs (prolyl hydroxylases), which in humans are PHD isoforms 1–3, and FIH (factor inhibiting HIF)] regulate HIF levels and activity. These enzymes are Fe(II)/2-oxoglutarate-dependent oxygenases, many of which are stimulated by ascorbate. We have investigated the ascorbate dependence of PHD2-catalysed hydroxylation of two prolyl hydroxylation sites in human HIF-1α, and of FIH-catalysed hydroxylation of asparaginyl hydroxylation sites in HIF-1α and in a consensus ankyrin repeat domain peptide. The initial rate and extent of hydroxylation was increased in the presence of ascorbate for each of these reactions. When ascorbate was replaced with structural analogues, the results revealed that the ascorbate side chain was not important in its contribution to HIF hydroxylase catalysis, whereas modifications to the ene-diol portion of the molecule negated the ability to promote hydroxylation. We investigated whether alternative reducing agents (glutathione and dithiothreitol) could be used to promote HIF hydroxylase activity, and found partial stimulation of hydroxylation in an apparently enzyme- and substrate-specific manner. The results raise the possibility of developing reducing agents targeted to specific HIF hydroxylase-catalysed reactions.
28
Horita, Shoichiro, John Scotti, Michael McDonough, Rok Sekirnik, Rashed Chowdhury, Tobias Krojer, Armin Thalhammer, WeiShen Aik, Udo Oppermann i Christopher Schofield. "Crystal structures of 2OG oxygenases involved in ribosomal protein hydroxylation". Acta Crystallographica Section A Foundations and Advances 70, a1 (5.08.2014): C304. http://dx.doi.org/10.1107/s2053273314096958.
Pełny tekst źródłaStreszczenie:
Post-translational modifications play diverse biological functions. Hydroxylation of collagen proteins has long been a recognised post-translational modification in eukaryotes. In the case of collagen, hydroxylation of prolyl residues, by 2-oxoglutarate and iron dependent enzymes (2OG oxygenases), in collagen proteins allows for the stabilisation of the collagen triple helix structure through conformational restraint and through the addition of a hydrogen bond donor. Additionally, hydroxylation of lysine side chains of collagen is required for cross-linking collagen (and possibly other proteins) in the extra-cellular matrix. Post-translational prolyl hydroxylation also plays a pivotal role in transcriptional regulation of the hypoxic response, as catalyzed by the hypoxia inducible factor / HIF prolyl hydroxylases (PHDs or EGLN enzymes). Recently, ribosomal protein hydroxylation catalyzed by 2OG- and Fe(II)-dependent oxygenases has been found to be a highly conserved post-translational modification in eukaryotes and prokaryotes (Ge et al and Loenarz et al). We present several crystal structures of 2OG oxygenases involved in ribosomal protein hydroxylation.
29
Lee, Mi-Jin, Hyun-Bum Kim, Yeo Joon Yoon, Kyuboem Han i Eung-Soo Kim. "Identification of a Cyclosporine-Specific P450 Hydroxylase Gene through Targeted Cytochrome P450 Complement (CYPome) Disruption in Sebekia benihana". Applied and Environmental Microbiology 79, nr 7 (25.01.2013): 2253–62. http://dx.doi.org/10.1128/aem.03722-12.
Pełny tekst źródłaStreszczenie:
ABSTRACTIt was previously proposed that regio-specific hydroxylation of an immunosuppressive cyclosporine (CsA) at the 4thN-methyl leucine is mediated by cytochrome P450 hydroxylase (CYP) in the rare actinomyceteSebekia benihana. This modification is thought to be the reason for the hair growth-promoting side effect without the immunosuppressive activity of CsA. ThroughS. benihanagenome sequencing andin silicoanalysis, we identified the complete cytochrome P450 complement (CYPome) ofS. benihana, including 21 CYPs and their electron transfer partners, consisting of 7 ferredoxins (FDs) and 4 ferredoxin reductases (FDRs). UsingEscherichia coliconjugation-basedS. benihanaCYPome-targeted disruption, all of the identified CYP, FD, and FDR genes inS. benihanawere individually inactivated. Among the 32S. benihanaexconjugant mutants tested, only a singleS. benihanaCYP mutant, ΔCYP-sb21, failed to exhibit CsA hydroxylation activity. The hydroxylation was restored by CYP-sb21 gene complementation. Since allS. benihanaFD and FDR disruption mutants maintained CsA hydroxylation activity, it can be concluded that CYP-sb21, a new member of the bacterial CYP107 family, is the only essential component of thein vivoregio-specific CsA hydroxylation process inS. benihana. Moreover, expression of an extra copy of the CYP-sb21 gene increased CsA hydroxylation in wild-typeS. benihanaand an NADPH-enrichedStreptomyces coelicolormutant, by 2-fold and 1.5-fold, respectively. These results show for the first time that regio-specific hydroxylation of CsA is carried out by a specific P450 hydroxylase present inS. benihana, and they set the stage for the biotechnological application of regio-specific CsA hydroxylation through heterologous CYP-sb21 expression.
30
Rodriguez, Javier, Cameron D. Haydinger, Daniel J. Peet, Lan K. Nguyen i Alex von Kriegsheim. "Asparagine Hydroxylation is a Reversible Post-translational Modification". Molecular & Cellular Proteomics 19, nr 11 (5.08.2020): 1777–89. http://dx.doi.org/10.1074/mcp.ra120.002189.
Pełny tekst źródłaStreszczenie:
Amino acid hydroxylation is a common post-translational modification, which generally regulates protein interactions or adds a functional group that can be further modified. Such hydroxylation is currently considered irreversible, necessitating the degradation and re-synthesis of the entire protein to reset the modification. Here we present evidence that the cellular machinery can reverse FIH-mediated asparagine hydroxylation on intact proteins. These data suggest that asparagine hydroxylation is a flexible and dynamic post-translational modification akin to modifications involved in regulating signaling networks, such as phosphorylation, methylation and ubiquitylation.
31
Biglieri, Edward G., i Claudio E. Kater. "17α-Hydroxylation Deficiency". Endocrinology and Metabolism Clinics of North America 20, nr 2 (czerwiec 1991): 257–68. http://dx.doi.org/10.1016/s0889-8529(18)30267-6.
Pełny tekst źródła
32
Holland, Herbert L., i Hedda K. Weber. "Enzymatic hydroxylation reactions". Current Opinion in Biotechnology 11, nr 6 (grudzień 2000): 547–53. http://dx.doi.org/10.1016/s0958-1669(00)00142-7.
Pełny tekst źródła
33
Broadwater, John A., Edward Whittle i John Shanklin. "Desaturation and Hydroxylation". Journal of Biological Chemistry 277, nr 18 (25.02.2002): 15613–20. http://dx.doi.org/10.1074/jbc.m200231200.
Pełny tekst źródła
34
Cowley, Ryan E., Li Tian i Edward I. Solomon. "Mechanism of O2 activation and substrate hydroxylation in noncoupled binuclear copper monooxygenases". Proceedings of the National Academy of Sciences 113, nr 43 (10.10.2016): 12035–40. http://dx.doi.org/10.1073/pnas.1614807113.
Pełny tekst źródłaStreszczenie:
Peptidylglycine α-hydroxylating monooxygenase (PHM) and dopamine β-monooxygenase (DβM) are copper-dependent enzymes that are vital for neurotransmitter regulation and hormone biosynthesis. These enzymes feature a unique active site consisting of two spatially separated (by 11 Å in PHM) and magnetically noncoupled copper centers that enables 1e– activation of O2 for hydrogen atom abstraction (HAA) of substrate C–H bonds and subsequent hydroxylation. Although the structures of the resting enzymes are known, details of the hydroxylation mechanism and timing of long-range electron transfer (ET) are not clear. This study presents density-functional calculations of the full reaction coordinate, which demonstrate: (i) the importance of the end-on coordination of superoxide to Cu for HAA along the triplet spin surface; (ii) substrate radical rebound to a CuII hydroperoxide favors the proximal, nonprotonated oxygen; and (iii) long-range ET can only occur at a late step with a large driving force, which serves to inhibit deleterious Fenton chemistry. The large inner-sphere reorganization energy at the ET site is used as a control mechanism to arrest premature ET and dictate the correct timing of ET.
35
Bradlow, H. Leon, i Jon J. Michnovicz. "A new approach to the prevention of breast cancer". Proceedings of the Royal Society of Edinburgh. Section B. Biological Sciences 95 (1989): 77–86. http://dx.doi.org/10.1017/s0269727000010575.
Pełny tekst źródłaStreszczenie:
SynopsisWhile the role of oestrogens in breast cancer has been recognised for over a century, until recently our understanding of the mechanism by which they act has been limited, despite zealous efforts on the part of many investigators to seek for differences in oestrogen levels or metabolism in cancer patients. Since the initiation of breast cancer occurs many years before the detection of overt disease, it seems reasonable to suggest that these earlier studies may have been carried out at the wrong stage of the disease. Using a time invariant radiometric procedure, we have established that of the three principal sites of oestrogen metabolism at C-2, C-16α, and C-17, only C-16α hydroxylation is elevated in women with breast cancer. Further studies in women at high risk for breast cancer for familial reasons showed that they have an elevated rate of 16α-hydroxylation. Parallel studies in mice with high and low rates of spontaneous mammary tumour formation show a close parallelism between the extent of 16α-hydroxylation and tumour incidence. Studies of 16α-hydroxyoestrone, the product of 16α-hydroxylation, have demonstrated that it is a unique oestrogen, capable of binding irreversibly to the oestrogen receptor and permanently activating it. Studies on the effects of diet and drugs on the extent of C-2 and C-16α hydroxylation have shown that while the former reaction is easily increased or decreased, the latter is refractory to treatment and behaves like a constitutive enzyme. Thus, treatment with cimetidine, obesity, or high fat diets decrease the extent of C-2 hydroxylation, while high protein diets, hyperthyroidism, smoking, or dioxins increase C-2 hydroxylation. In contrast, 16α-hydroxylation is essentially unchanged in any of these conditions.A link between increased C-2 hydroxylation and decreased levels of breast and endometrial cancer is suggested by epidemiological studies in smokers. Conversely, decreases in this reaction as in obesity are associated with increased risk for these tumours. The aim of these studies is to develop a safe prophylactic regimen which will increase C-2 hydroxylation, resulting in a decrease in active oestrogen and a lower tumour incidence.
36
Prasetyoko, Didik, Cholifah Endah Royani, Hamzah Fansuri, Zainab Ramli i Hadi Nur. "CATALYTIC PERFORMANCES OF Fe2O3/TS-1 CATALYST IN PHENOL HYDROXYLATION REACTION". Indonesian Journal of Chemistry 10, nr 2 (21.07.2010): 149–55. http://dx.doi.org/10.22146/ijc.21452.
Pełny tekst źródłaStreszczenie:
Hydroxylation reaction of phenol into diphenol, such as hydroquinone and catechol, has a great role in many industrial applications. Phenol hydroxylation reaction can be carried out using Titanium Silicalite-1 (TS-1) as catalyst and H2O2 as an oxidant. TS-1 catalyst shows high activity and selectivity for phenol hydroxylation reaction. However, its hydrophobic sites lead to slow H2O2 adsorption toward the active site of TS-1. Consequently, the reaction rate of phenol hydroxylation reaction is tends to be low. Addition of metal oxide Fe2O3 enhanced hydrophilicity of TS-1 catalyst. Liquid phase catalytic phenol hydroxylation using hydrogen peroxide as oxidant was carried out over iron (III) oxide-modified TS-1 catalyst (Fe2O3/TS-1), that were prepared by impregnation method using iron (III) nitrate as precursor and characterized by X-ray diffraction, infrared spectroscopy, nitrogen adsorption, pyridine adsorption, and hydrophilicity techniques. Catalysts 1Fe2O3/TS-1 showed maximum catalytic activity of hydroquinone product. In this research, the increase of hydroquinone formation rate is due to the higher hydrophilicity of Fe2O3/TS-1 catalysts compare to the parent catalyst, TS-1. Keywords: Fe2O3/TS-1, hydrophilic site, phenol hydroxylation
37
Fujii, Kazunori K., Yuki Taga, Yusuke K. Takagi, Ryo Masuda, Shunji Hattori i Takaki Koide. "The Thermal Stability of the Collagen Triple Helix Is Tuned According to the Environmental Temperature". International Journal of Molecular Sciences 23, nr 4 (12.02.2022): 2040. http://dx.doi.org/10.3390/ijms23042040.
Pełny tekst źródłaStreszczenie:
Triple helix formation of procollagen occurs in the endoplasmic reticulum (ER) where the single-stranded α-chains of procollagen undergo extensive post-translational modifications. The modifications include prolyl 4- and 3-hydroxylations, lysyl hydroxylation, and following glycosylations. The modifications, especially prolyl 4-hydroxylation, enhance the thermal stability of the procollagen triple helix. Procollagen molecules are transported to the Golgi and secreted from the cell, after the triple helix is formed in the ER. In this study, we investigated the relationship between the thermal stability of the collagen triple helix and environmental temperature. We analyzed the number of collagen post-translational modifications and thermal melting temperature and α-chain composition of secreted type I collagen in zebrafish embryonic fibroblasts (ZF4) cultured at various temperatures (18, 23, 28, and 33 °C). The results revealed that thermal stability and other properties of collagen were almost constant when ZF4 cells were cultured below 28 °C. By contrast, at a higher temperature (33 °C), an increase in the number of post-translational modifications and a change in α-chain composition of type I collagen were observed; hence, the collagen acquired higher thermal stability. The results indicate that the thermal stability of collagen could be autonomously tuned according to the environmental temperature in poikilotherms.
38
Uehara, Shotaro, Toru Oshio, Kazuyuki Nakanishi, Etsuko Tomioka, Miyu Suzuki, Takashi Inoue, Yasuhiro Uno, Erika Sasaki i Hiroshi Yamazaki. "Survey of Drug Oxidation Activities in Hepatic and Intestinal Microsomes of Individual Common Marmosets, a New Nonhuman Primate Animal Model". Current Drug Metabolism 20, nr 2 (30.04.2019): 103–13. http://dx.doi.org/10.2174/1389200219666181003143312.
Pełny tekst źródłaStreszczenie:
Background: Common marmosets (Callithrix jacchus) are potentially useful nonhuman primate models for preclinical studies. Information for major drug-metabolizing cytochrome P450 (P450) enzymes is now available that supports the use of this primate species as an animal model for drug development. Here, we collect and provide an overview of information on the activities of common marmoset hepatic and intestinal microsomes with respect to 28 typical human P450 probe oxidations. Results: Marmoset P450 2D6/8-dependent R-metoprolol O-demethylation activities in hepatic microsomes were significantly correlated with those of midazolam 1′- and 4-hydroxylations, testosterone 6β-hydroxylation, and progesterone 6β-hydroxylation, which are probe reactions for marmoset P450 3A4/5/90. In marmosets, the oxidation activities of hepatic microsomes and intestinal microsomes were roughly comparable for midazolam and terfenadine. Overall, multiple forms of marmoset P450 enzymes in livers and intestines had generally similar substrate recognition functionalities to those of human and/or cynomolgus monkey P450 enzymes. Conclusion: The marmoset could be a model animal for humans with respect to the first-pass extraction of terfenadine and related substrates. These findings provide a foundation for understanding individual pharmacokinetic and toxicological results in nonhuman primates as preclinical models and will help to further support understanding of the molecular mechanisms of human P450 function.
39
Nguyen, Xuandai, Mong-Heng Wang, Komandla M. Reddy, John R. Falck i Michal Laniado Schwartzman. "Kinetic profile of the rat CYP4A isoforms: arachidonic acid metabolism and isoform-specific inhibitors". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 276, nr 6 (1.06.1999): R1691—R1700. http://dx.doi.org/10.1152/ajpregu.1999.276.6.r1691.
Pełny tekst źródłaStreszczenie:
20-Hydroxyeicosatetraenoic acid (HETE), the cytochrome P-450 (CYP) 4A ω-hydroxylation product of arachidonic acid, has potent biological effects on renal tubular and vascular functions and on the control of arterial pressure. We have expressed high levels of the rat CYP4A1, -4A2, -4A3, and -4A8 cDNAs, using baculovirus and Sf 9 insect cells. Arachidonic acid ω- and ω-1-hydroxylations were catalyzed by three of the CYP4A isoforms; the highest catalytic efficiency of 947 nM−1 ⋅ min−1for CYP4A1 was followed by 72 and 22 nM−1 ⋅ min−1for CYP4A2 and CYP4A3, respectively. CYP4A2 and CYP4A3 exhibited an additional arachidonate 11,12-epoxidation activity, whereas CYP4A1 operated solely as an ω-hydroxylase. CYP4A8 did not catalyze arachidonic or linoleic acid but did have a detectable lauric acid ω-hydroxylation activity. The inhibitory activity of various acetylenic and olefinic fatty acid analogs revealed differences and indicated isoform-specific inhibition. These studies suggest that CYP4A1, despite its low expression in extrahepatic tissues, may constitute the major source of 20-HETE synthesis. Moreover, the ability of CYP4A2 and -4A3 to catalyze the formation of two opposing biologically active metabolites, 20-HETE and 11,12-epoxyeicosatrienoic acid, may be of great significance to the regulation of vascular tone.
40
Postlind, H., i K. Wikvall. "Purification of a cytochrome P-450 from pig kidney microsomes catalysing the 25-hydroxylation of vitamin D3". Biochemical Journal 253, nr 2 (15.07.1988): 549–52. http://dx.doi.org/10.1042/bj2530549.
Pełny tekst źródłaStreszczenie:
Cytochrome P-450 catalysing 25-hydroxylation of vitamin D3 was purified from pig kidney microsomes. The enzyme fraction contained 7 nmol of cytochrome P-450/mg of protein and showed only one protein band with an apparent Mr of 50,500 upon SDS/polyacrylamide-gel electrophoresis. The purified cytochrome P-450 catalysed 25-hydroxylation of vitamin D3 up to 1,000 times more efficiently, and 25-hydroxylation of 1 alpha-hydroxyvitamin D3 up to 4000 times more efficiently, than the microsomes. The cytochrome P-450 required microsomal NADPH-cytochrome P-450 reductase for catalytic activity. Mitochondrial ferredoxin and ferredoxin reductase could not replace microsomal NADPH-cytochrome P-450 reductase. The enzyme preparation showed no detectable 25-hydroxylase activity towards vitamin D2 or 1 alpha-hydroxylase activity towards 25-hydroxyvitamin D3. CO inhibited the 25-hydroxylation by more than 85%. Mannitol, hydroquinone, catalase and superoxide dismutase did not affect the 25-hydroxylation. The possible role of the kidney microsomal cytochrome P-450 in the metabolism of vitamin D3 is discussed.
41
Dahlbäck-Sjöberg, H., I. Björkhem i H. M. Princen. "Selective inhibition of mitochondrial 27-hydroxylation of bile acid intermediates and 25-hydroxylation of vitamin D3 by cyclosporin A". Biochemical Journal 293, nr 1 (1.07.1993): 203–6. http://dx.doi.org/10.1042/bj2930203.
Pełny tekst źródłaStreszczenie:
It was demonstrated recently that cyclosporin A blocks bile acid synthesis in cultured rat and human hepatocytes by specific inhibition of chenodeoxycholic acid formation. The site of inhibition was found to be the 27-hydroxylation of cholesterol catalysed by the liver mitochondrial 27-hydroxylase [Princen, Meijer, Wolthers, Vonk and Kuipers (1991) Biochem J. 275, 501-505]. In this paper the mechanism by which cyclosporin A blocks mitochondrial 27-hydroxylation was further investigated. It is shown that cyclosporin A inhibited 27-hydroxylation of bile acid intermediates, depending on their polarity. In isolated rat liver mitochondria, 27-hydroxylation of cholesterol was dose-dependently blocked by the drug, giving half-maximal inhibition at 4 microM, whereas 27-hydroxylation of 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha-triol was not affected. A similar observation was made using electrophoretically homogeneous cytochrome P-450(27) isolated from rabbit liver mitochondria, excluding the possibility that cyclosporin A interfered with transport of substrates into the mitochondrion. Kinetic studies showed that inhibition of the 27-hydroxylation of cholesterol by cyclosporin A was of a non-competitive type. The drug also inhibited the 25-hydroxylase activity towards vitamin D3, catalysed by the same enzyme preparation, to the same extent as 27-hydroxylation of cholesterol. These results suggest that cyclosporin A may interfere with binding of cholesterol, but not of 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha-triol, to the active site of the enzyme. These data provide an explanation for the selective inhibition of chenodeoxycholic acid synthesis.
42
Hadama, Atsuko, Ichiro Ieiri, Toshihiro Morita, Miyuki Kimura, Akinori Urae, Shin Irie, Tatsuya Kaneda i in. "P-Hydroxylation of Phenobarbital: Relationship to (s)-Mephenytoin Hydroxylation (CYP2C19) Polymorphism". Therapeutic Drug Monitoring 23, nr 2 (kwiecień 2001): 115–18. http://dx.doi.org/10.1097/00007691-200104000-00004.
Pełny tekst źródła
43
Liu, Yonghai, Yang Yu, Chengyu Sun, Yiwei Fu, Zhiguo Mang, Lei Shi i Hao Li. "Transition-Metal Free Chemoselective Hydroxylation and Hydroxylation–Deuteration of Heterobenzylic Methylenes". Organic Letters 22, nr 20 (7.10.2020): 8127–31. http://dx.doi.org/10.1021/acs.orglett.0c03108.
Pełny tekst źródła
44
Hinz, John R. R., Micheal D. K. Owen i Michael Barrett. "Nicosulfuron, primisulfuron, and bentazon hydroxylation by corn (Zea mays), woolly cupgrass (Eriochloa villosa), and shattercane (Sorghum bicolor) cytochrome P-450". Weed Science 45, nr 4 (sierpień 1997): 474–80. http://dx.doi.org/10.1017/s004317450008869x.
Pełny tekst źródłaStreszczenie:
Microsomes (100,000 g pellet containing mixed membrane fractions but primarily endoplasmic reticulum) were isolated from shoots of corn, shattercane, and woolly cupgrass grown from naphthalic anhydride treated or untreated seed to determine if metabolism of bentazon, nicosulfuron, and primisulfuron could be demonstrated in the preparations. Corn is tolerant of all three herbicides, shattercane is tolerant of bentazon, and woolly cupgrass is tolerant of bentazon and primisulfuron. Naphthalic anhydride treatment was required for detectable bentazon, nicosulfuron, and primisulfuron hydroxylation in corn microsomes and for bentazon hydroxylation in woolly cupgrass microsomes. Bentazon hydroxylation was low, but detectable, in microsomes from shattercane shoots without naphthalic anhydride treatment. Naphthalic anhydride-treated corn microsomes hydroxylated 292, 120, and 52 pmol mg−1protein min−1of bentazon, nicosulfuron, and primisulfuron, respectively. Primisulfuron (19 pmol mg−1protein min−1), but not nicosulfuron, was hydroxylated in woolly cupgrass microsomes. Neither nicosulfuron nor primisulfuron was hydroxylated in shattercane microsomes. Bentazon and primisulfuron inhibited nicosulfuron hydroxylation in corn microsomes. Bentazon, but not nicosulfuron, also inhibited primisulfuron hydroxylation in the corn microsomes. This indicates that the three herbicides can interact at the same cytochrome P-450(s) in corn. Primisulfuron hydroxylation was not inhibited by either bentazon or nicosulfuron in woolly cupgrass microsomes. This suggests that the cytochrome P-450(s) for primisulfuron hydroxylation are different between corn and woolly cupgrass. Also, bentazon hydroxylation in corn and shattercane microsomes was inhibited by the cytochrome P-450 inhibitor tetcyclasis, while that in woolly cupgrass was not. Again, this suggests a difference in the cytochrome P-450(s) responsible for bentazon metabolism among the species. Although absolute conclusions comparing in vitro microsomal activities to whole plant herbicide tolerance cannot be made because it is unknown whether the same cytochrome P-450(s) are studied in microsomes from naphthalic anhydride-treated tissue as are responsible for in vivo herbicide metabolism, there was a broad correlation between metabolism of a particular herbicide in microsomes of a species and the species' tolerance of that herbicide.
45
Junttila, O., R. W. King, A. Poole, G. Kretschmer, R. P. Pharis i L. T. Evans. "Regulation in Lolium temulentum of the Metabolism of Gibberellin A20 and Gibberellin A1 by 16,17-Dihydro GA5 and by the Growth Retardant, LAB 198 999". Functional Plant Biology 24, nr 3 (1997): 359. http://dx.doi.org/10.1071/pp96031.
Pełny tekst źródłaStreszczenie:
The ring D-modified gibberellin [GA], 16,17-dihydro GA5, can retard stem growth in Lolium temulentum L. while promoting flowering (Evans et al., 1994, Planta193, 107–114). Using [1,2,3-3 H]GA20 to study the final biosynthetic step to GA1 (a known effector of shoot elongation in higher plants), it was shown that C-3b-hydroxylation of GA20 to GA1 is blocked by 16,17-dihydro GA5 but is little affected by GA5. Another late-stage biosynthetic inhibitor, the acylcyclohexanedione, LAB 198 999, also blocked GA1 formation. Furthermore, endogenous levels of GA20 built up after application of 16,17-dihydro GA5. Consequently, growth retardation by 16,17-dihydro GA5 and LAB 198 999 is likely to be the result of their inhibition of GA20 3b-hydroxylation to GA1. Another fate for GA20 in Lolium is its C-2b-hydroxylation to growth-inactive GA29. This conversion was also inhibited by 16,17-dihydro GA5 but less so by LAB 198 999. The analogous step involving 2b-hydroxylation of GA1 to GA8 appeared to be insensitive to either growth retardant. When [3H]GA20 was injected into the cavity within the young intact sheathing leaves, there was an appreciable metabolism of this GA20 to GA1 and thence to GA8 (ca 10% and 30% respectively within 5 h). For excised shoot tips, however, [3H]GA20 was converted rapidly and virtually completely to GA29 in 3–5 h. Interestingly, with these excised shoot tips, GA3 and GA5 as well as 16,17-dihydro GA5 when applied via the agar strongly inhibited 2b-hydroxylation of GA20 to GA29. In contrast, while 16,17-dihydro GA5 blocked GA20 metabolism to GA29 in intact sheath/stem tissue, this conversion was not inhibited by GA5. These differences in structural specificity for GAs which inhibit 2b-hydroxylation as opposed to 3b-hydroxylation are in accordance with these two Ring-A hydroxylation steps being catalysed by different enzymes. Finally, the differences in GA20 metabolism between intact versus excised tissue raise the possibility that tissue wounding with excision enhanced the activity of the GA20 2b-hydroxylase(s).
46
Lawton, Margot, Ming Tong, Fusun Gundogan, Jack R. Wands i Suzanne M. de la Monte. "Aspartyl-(asparaginyl) β-Hydroxylase, Hypoxia-Inducible Factor-1α and Notch Cross-Talk in Regulating Neuronal Motility". Oxidative Medicine and Cellular Longevity 3, nr 5 (2010): 347–56. http://dx.doi.org/10.4161/oxim.3.5.13296.
Pełny tekst źródłaStreszczenie:
Aspartyl-(Asparaginyl)-β-Hydroxylase (AAH ) promotes cell motility by hydroxylating Notch. Insulin and insulin-like growth factor, type 1 (IGF-I) stimulate AAH through Erk MAP K and phosphoinositol-3-kinase-Akt (PI3K-Akt). However, hypoxia/oxidative stress may also regulate AAH . Hypoxia-inducible factor-1alpha (HIF-1α) regulates cell migration, signals through Notch, and is regulated by hypoxia/oxidative stress, insulin/IGF signaling and factor inhibiting HIF-1α (FIH) hydroxylation. To examine cross-talk between HIF-1α and AAH , we measured AAH , Notch-1, Jagged-1, FIH, HIF-1α, HIF-1β and the hairy and enhancer of split 1 (HE S-1) transcription factor expression and directional motility in primitive neuroectodermal tumor 2 (PNET2) human neuronal cells that were exposed to H2O2or transfected with short interfering RNA duplexes (siRNA) targeting AAH , Notch-1 or HIF-1α. We found that: (1) AAH , HIF-1α and neuronal migration were stimulated by H2O2; (2) si-HIF-1α reduced AAH expression and cell motility; (3) si-AAH inhibited Notch and cell migration, but not HIF-1α and (4) si-Notch-1 increased FIH and inhibited HIF-1α. These findings suggest that AAH and HIF-1α crosstalk within a hydroxylation-regulated signaling pathway that may be transiently driven by oxidative stress and chronically regulated by insulin/IGF signaling.
47
Ma, Li, Lei Du, Hui Chen, Yue Sun, Shan Huang, Xianliang Zheng, Eung-Soo Kim i Shengying Li. "Reconstitution of theIn VitroActivity of the Cyclosporine-Specific P450 Hydroxylase from Sebekia benihana and Development of a Heterologous Whole-Cell Biotransformation System". Applied and Environmental Microbiology 81, nr 18 (6.07.2015): 6268–75. http://dx.doi.org/10.1128/aem.01353-15.
Pełny tekst źródłaStreszczenie:
ABSTRACTThe cytochrome P450 enzyme CYP-sb21 fromSebekia benihanais capable of catalyzing the site-specific hydroxylation of the immunosuppressant cyclosporine (CsA), leading to the single product γ-hydroxy-N-methyl-l-Leu4-CsA (CsA-4-OH). Unlike authentic CsA, this hydroxylated CsA shows significantly reduced immunosuppressive activity while it retains a side effect of CsA, the hair growth stimulation effect. Although CYP-sb21 was previously identified to be responsible for CsA-specific hydroxylationin vivo, thein vitroactivity of CYP-sb21 has yet to be established for a deeper understanding of this P450 enzyme and further reaction optimization. In this study, we reconstituted thein vitroactivity of CYP-sb21 by using surrogate redox partner proteins of bacterial and cyanobacterial origins. The highest CsA site-specific hydroxylation activity by CYP-sb21 was observed when it was partnered with the cyanobacterial redox system composed ofseFdx andseFdR fromSynechococcus elongatusPCC 7942. The best bioconversion yields were obtained in the presence of 10% methanol as a cosolvent and an NADPH regeneration system. A heterologous whole-cell biocatalyst usingEscherichia coliwas also constructed, and the permeability problem was solved by usingN-cetyl-N,N,N-trimethylammonium bromide (CTAB). This work provides a useful example for reconstituting a hybrid P450 system and developing it into a promising biocatalyst for industrial application.
48
Varma, Sameer, Joseph P. R. O. Orgel i Jay D. Schieber. "Contrasting Local and Macroscopic Effects of Collagen Hydroxylation". International Journal of Molecular Sciences 22, nr 16 (23.08.2021): 9068. http://dx.doi.org/10.3390/ijms22169068.
Pełny tekst źródłaStreszczenie:
Collagen is heavily hydroxylated. Experiments show that proline hydroxylation is important to triple helix (monomer) stability, fibril assembly, and interaction of fibrils with other molecules. Nevertheless, experiments also show that even without hydroxylation, type I collagen does assemble into its native D-banded fibrillar structure. This raises two questions. Firstly, even though hydroxylation removal marginally affects macroscopic structure, how does such an extensive chemical change, which is expected to substantially reduce hydrogen bonding capacity, affect local structure? Secondly, how does such a chemical perturbation, which is expected to substantially decrease electrostatic attraction between monomers, affect collagen’s mechanical properties? To address these issues, we conduct a benchmarked molecular dynamics study of rat type I fibrils in the presence and absence of hydroxylation. Our simulations reproduce the experimental observation that hydroxylation removal has a minimal effect on collagen’s D-band length. We also find that the gap-overlap ratio, monomer width and monomer length are minimally affected. Surprisingly, we find that de-hydroxylation also has a minor effect on the fibril’s Young’s modulus, and elastic stress build up is also accompanied by tightening of triple-helix windings. In terms of local structure, de-hydroxylation does result in a substantial drop (23%) in inter-monomer hydrogen bonding. However, at the same time, the local structures and inter-monomer hydrogen bonding networks of non-hydroxylated amino acids are also affected. It seems that it is this intrinsic plasticity in inter-monomer interactions that preclude fibrils from undergoing any large changes in macroscopic properties. Nevertheless, changes in local structure can be expected to directly impact collagen’s interaction with extra-cellular matrix proteins. In general, this study highlights a key challenge in tissue engineering and medicine related to mapping collagen chemistry to macroscopic properties but suggests a path forward to address it using molecular dynamics simulations.
49
Chen, Zhifeng, Jie Chen, Nana Ma, Haifeng Zhou i Zhiqi Cong. "Selective hydroxylation of naphthalene using the H2O2-dependent engineered P450BM3 driven by dual-functional small molecules". Journal of Porphyrins and Phthalocyanines 22, nr 09n10 (21.08.2018): 831–36. http://dx.doi.org/10.1142/s108842461850061x.
Pełny tekst źródłaStreszczenie:
We herein report the H2O2-dependent selective hydroxylation of naphthalene catalyzed by engineered P450BM3 with the assistance of dual-functional small molecules (DFSMs). The mutation at position 268 significantly improved the hydroxylation activity of P450BM3, which is quite different from those engineered P450BM3 peroxygenases and NADPH-dependent P450BM3 mutants previously reported, implicating the unique role of the residue at position 268. This study provides a potential approach to develop the practical hydroxylation biocatalyst of P450s for aromatic hydrocarbons using the DFSM-facilitated P450BM3-H2O2 system.
50
Niwa, Toshiro, Kanae Narita, Ayaka Okamoto, Norie Murayama i Hiroshi Yamazaki. "Comparison of Steroid Hormone Hydroxylations by and Docking to Human Cytochromes P450 3A4 and 3A5". Journal of Pharmacy & Pharmaceutical Sciences 22 (24.07.2019): 332–39. http://dx.doi.org/10.18433/jpps30558.
Pełny tekst źródłaStreszczenie:
Purpose: Hydroxylation activity at the 6β-position of steroid hormones (testosterone, progesterone, and cortisol) by human cytochromes P450 (P450 or CYP) 3A4 and CYP3A5 and their molecular docking energy values were compared to understand the catalytic properties of the major forms of human CYP3A, namely, CYP3A4 and CYP3A5. Methods: Testosterone, progesterone, and cortisol 6β-hydroxylation activities of recombinant CYP3A4 and CYP3A5 were determined by liquid chromatography. Docking simulations of these substrates to the heme moiety of reported crystal structures of CYP3A4 (Protein Data Bank code ITQN) and CYP3A5 (6MJM) were conducted. Results: Michaelis constants (Km) for CYP3A5-mediated 6β-hydroxylation of testosterone and progesterone were approximately twice those for CYP3A4, whereas the value for cortisol 6β-hydroxylation mediated by CYP3A5 was similar to the value for that by CYP3A4. Maximal velocities (Vmax) of the three steroid hormones 6β-hydroxylation catalyzed by CYP3A5 were 30%-63% of those by CYP3A4. Thus, Vmax/ Km values of these hormones for CYP3A5 resulted in 22%-31% of those for CYP3A4. The differences in the docking energies between CYP3A4 and CYP3A5 for steroid hormones were slightly correlated to the logarithm of CYP3A5/CYP3A4 ratios for Km values (substrate affinity). Conclusions: The Vmax, rather than Km values, for CYP3A5-mediated 6β-hydroxylation of three steroid hormones were different from those for CYP3A4. Molecular docking simulations could partially explain the differences in the accessibility of substrates to the heme moiety of human CYP3A molecules, resulting in the enzymatic affinity of CYP3A4 and CYP3A5.