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1
Alin, P., H. Jensson, E. Cederlund, H. Jörnvall e B. Mannervik. "Cytosolic glutathione transferases from rat liver. Primary structure of class alpha glutathione transferase 8-8 and characterization of low-abundance class Mu glutathione transferases". Biochemical Journal 261, n. 2 (15 luglio 1989): 531–39. http://dx.doi.org/10.1042/bj2610531.
Testo completoAbstract (sommario):
Six GSH transferases with neutral/acidic isoelectric points were purified from the cytosol fraction of rat liver. Four transferases are class Mu enzymes related to the previously characterized GSH transferases 3-3, 4-4 and 6-6, as judged by structural and enzymic properties. Two additional GSH transferases are distinguished by high specific activities with 4-hydroxyalk-2-enals, toxic products of lipid peroxidation. The most abundant of these two enzymes, GSH transferase 8-8, a class Alpha enzyme, has earlier been identified in rat lung and kidney. The amino acid sequence of subunit 8 was determined and showed a typical class Alpha GSH transferase structure including an N-acetylated N-terminal methionine residue.
2
Stockman, P. K., G. J. Beckett e J. D. Hayes. "Identification of a basic hybrid glutathione S-transferase from human liver. Glutathione S-transferase δ is composed of two distinct subunits (B1 and B2)". Biochemical Journal 227, n. 2 (15 aprile 1985): 457–65. http://dx.doi.org/10.1042/bj2270457.
Testo completoAbstract (sommario):
The purification of a hybrid glutathione S-transferase (B1 B2) from human liver is described. This enzyme has an isoelectric point of 8.75 and the B1 and B2 subunits are distinguishable immunologically and are ionically distinct. Hybridization experiments demonstrated that B1 B1 and B2 B2 could be resolved by CM-cellulose chromatography and have pI values of 8.9 and 8.4 respectively. Transferase B1 B2, and the two homodimers from which it is formed, are electrophoretically and immunochemically distinct from the neutral enzyme (transferase mu) and two acidic enzymes (transferases rho and lambda). Sodium dodecyl sulphate/polyacrylamide-gel electrophoresis demonstrated that B1 and B2 both have an Mr of 26 000, whereas, in contrast, transferase mu comprises subunits of Mr 27 000 and transferases rho and lambda both comprise subunits of Mr 24 500. Antisera raised against B1 or B2 monomers did not cross-react with the neutral or acidic glutathione S-transferases. The identity of transferase B1 B2 with glutathione S-transferase delta prepared by the method of Kamisaka, Habig, Ketley, Arias & Jakoby [(1975) Eur. J. Biochem. 60, 153-161] has been demonstrated, as well as its relationship to other previously described transferases.
3
Meyer, D. J., E. Lalor, B. Coles, A. Kispert, P. Ålin, B. Mannervik e B. Ketterer. "Single-step purification and h.p.l.c. analysis of glutathione transferase 8–8 in rat tissues". Biochemical Journal 260, n. 3 (15 giugno 1989): 785–88. http://dx.doi.org/10.1042/bj2600785.
Testo completoAbstract (sommario):
GSSG selectively elutes two GSH transferases from a mixture of rat GSH transferases bound to a GSH-agarose affinity matrix. One is a form of GSH transferase 1-1 and the other is shown to be GSH transferase 8-8. By using tissues that lack this form of GSH transferase 1-1 (e.g. lung), GSH transferase 8-8 may thus be purified from cytosol in a single step. Quantitative analysis of the tissue distribution of GSH transferase 8-8 was obtained by h.p.l.c.
4
Yamamoto, Miyako, Emili Cid e Fumiichiro Yamamoto. "ABO blood group A transferases catalyze the biosynthesis of FORS blood group FORS1 antigen upon deletion of exon 3 or 4". Blood Advances 1, n. 27 (20 dicembre 2017): 2756–66. http://dx.doi.org/10.1182/bloodadvances.2017009795.
Testo completoAbstract (sommario):
Key PointsABO blood group A transferases possess intrinsic FS activity upon deletion of exon 3 or 4 of A transferase messenger RNAs. Cointroduction of exon 3 or 4 deletion and GlyGlyAla substitution synergistically confers human A transferases with strong FS activity.
5
Tan, K. H., D. J. Meyer, N. Gillies e B. Ketterer. "Detoxification of DNA hydroperoxide by glutathione transferases and the purification and characterization of glutathione transferases of the rat liver nucleus". Biochemical Journal 254, n. 3 (15 settembre 1988): 841–45. http://dx.doi.org/10.1042/bj2540841.
Testo completoAbstract (sommario):
DNA peroxidized by exposure to ionizing radiation in the presence of oxygen is a substrate for the Se-independent GSH peroxidase activity of several GSH transferases, GSH transferases 5-5, 3-3 and 4-4 being the most active in the rat liver soluble supernatant fraction (500, 35 and 20 nmol/min per mg of protein respectively) and GSH transferases mu and pi the most active, so far found, in the human liver soluble supernatant fraction (80 and 10 nmol/min per mg respectively). Although the GSH transferase content of the rat nucleus was found to be much lower than that of the soluble supernatant, nuclear GSH transferases are likely to be more important in the detoxification of DNA hydroperoxide produced in vivo. Two nuclear fractions were studied, one extracted with 0.075 M-saline/0.025 M-EDTA, pH 8.0, and the other extracted from the residue with 8.5 M-urea. The saline/EDTA fraction contained subunits 1, 2, 3, 4 and a novel subunit, similar but not identical to 5, provisionally referred to as 5*, in the proportions 40:25:5:5:25 respectively. The 8.5 M-urea-extracted fraction contained principally subunit 5* together with a small amount of subunit 6 in the proportion 95:5 respectively. GSH transferase 5*-5* purified from the 8.5 M-urea extract has the highest activity towards DNA hydroperoxide of any GSH transferase so far studied (1.5 mumol/min per mg). A Se-dependent GSH peroxidase fraction from rat liver was also active towards DNA hydroperoxide; however, since this enzyme accounts for only 14% of the GSH peroxidase activity detectable in the nucleus, GSH transferases may be the more important source of this activity. The possible role of GSH transferases, in particular GSH transferase 5*-5*, in DNA repair is discussed.
6
Peters, W. H. M., H. M. J. Roelofs, F. M. Nagengast e J. H. M. van Tongeren. "Human intestinal glutathione S-transferases". Biochemical Journal 257, n. 2 (15 gennaio 1989): 471–76. http://dx.doi.org/10.1042/bj2570471.
Testo completoAbstract (sommario):
Cytosolic glutathione S-transferases were purified from the epithelial cells of human small and large intestine. These preparations were characterized with regard to specific activities, subunit and isoenzyme composition. Isoenzyme composition and specific activity showed little variation from proximal to distal small intestine. Specific activities of hepatic and intestinal enzymes from the same patient were comparable. Hepatic enzymes were mainly composed of 25 kDa subunits. Transferases from small intestine contained 24 and 25 kDa subunits, in variable amounts. Colon enzymes were composed of 24 kDa subunits. In most preparations, however, minor amounts of 27 and 27.5 kDa subunits were detectable. Separation into isoforms by isoelectric focusing revealed striking differences: glutathione S-transferases from liver were mainly basic or neutral, enzymes from small intestine were basic, neutral and acidic, whereas large intestine contained acidic isoforms only. The intestinal acidic transferase most probably was identical with glutathione S-transferase Pi, isolated from human placenta. In the hepatic preparation, this isoform was hardly detectable. The specific activity of glutathione S-transferase showed a sharp fall from small to large intestine. In proximal and distal colon, activity seemed to be about equal. In the ascending colon there might be a relationship between specific activity of glutathione S-transferases and age of the patient, activity decreasing with increasing age.
7
Danielson, U. H., H. Esterbauer e B. Mannervik. "Structure-activity relationships of 4-hydroxyalkenals in the conjugation catalysed by mammalian glutathione transferases". Biochemical Journal 247, n. 3 (1 novembre 1987): 707–13. http://dx.doi.org/10.1042/bj2470707.
Testo completoAbstract (sommario):
The substrate specificities of 15 cytosolic glutathione transferases from rat, mouse and man have been explored by use of a homologous series of 4-hydroxyalkenals, extending from 4-hydroxypentenal to 4-hydroxypentadecenal. Rat glutathione transferase 8-8 is exceptionally active with the whole range of 4-hydroxyalkenals, from C5 to C15. Rat transferase 1-1, although more than 10-fold less efficient than transferase 8-8, is the second most active transferase with the longest chain length substrates. Other enzyme forms showing high activities with these substrates are rat transferase 4-4 and human transferase mu. The specificity constants, kcat./Km, for the various enzymes have been determined with the 4-hydroxyalkenals. From these constants the incremental Gibbs free energy of binding to the enzyme has been calculated for the homologous substrates. The enzymes responded differently to changes in the length of the hydrocarbon side chain and could be divided into three groups. All glutathione transferases displayed increased binding energy in response to increased hydrophobicity of the substrate. For some of the enzymes, steric limitations of the active site appear to counteract the increase in binding strength afforded by increased chain length of the substrate. Comparison of the activities with 4-hydroxyalkenals and other activated alkenes provides information about the active-site properties of certain glutathione transferases. The results show that the ensemble of glutathione transferases in a given species may serve an important physiological role in the conjugation of the whole range of 4-hydroxyalkenals. In view of its high catalytic efficiency with all the homologues, rat glutathione transferase 8-8 appears to have evolved specifically to serve in the detoxication of these reactive compounds of oxidative metabolism.
8
Kurz, M. A., T. D. Boyer, R. Whalen, T. E. Peterson e D. G. Harrison. "Nitroglycerin metabolism in vascular tissue: role of glutathione S-transferases and relationship between NO. and NO2– formation". Biochemical Journal 292, n. 2 (1 giugno 1993): 545–50. http://dx.doi.org/10.1042/bj2920545.
Testo completoAbstract (sommario):
Nitroglycerin is a commonly employed pharmacological agent which produces vasodilatation by release of nitric oxide (NO.). The mechanism by which nitroglycerin releases NO. remains undefined. Recently, glutathione S-transferases have been implicated as important contributors to this process. They are known to release NO2- from nitroglycerin, but have not been shown to release NO.. The present studies were designed to examine the role of endogenous glutathione S-transferases in this metabolic process. Homogenates of dog carotid artery were incubated anaerobically with nitroglycerin, and NO. and NO2- production was determined by chemiluminescence. The role of glutathione S-transferases was studied by incubating homogenates with nitroglycerin in the presence of 1 mM GSH or 1 mM S-hexyl-glutathione, a potent inhibitor of glutathione S-transferases. Homogenates released 163 pmol of NO./h per mg of protein from nitroglycerin, and 2370 pmol of NO2-/h per mg. Adding GSH decreased NO. production by 82% and increased NO2- production by 98%. S-Hexylglutathione inhibited glutathione S-transferase activity by 96% and decreased NO2- production by 78%, but had no effect on NO. release. A linear relationship between glutathione S-transferase activity and NO2- production was observed, whereas glutathione S-transferase activity and NO. release were unrelated. Western-blot analysis demonstrated that dog carotid vascular smooth muscle contained Pi and Mu forms of glutathione S-transferases, with a predominance of the former. Purified preparations of human Pi and rat Mu isoforms metabolized nitroglycerin only to NO2- and not to NO.. On the basis of these findings, we conclude that (1) glutathione S-transferases do not contribute to the bioconversion of nitroglycerin to NO., but instead act as a degradative pathway for nitroglycerin, and (2) the release of NO. from nitroglycerin is not dependent on the formation of NO2-.
9
Wang, Qiang-Qiang, Kai He, Muhammad-Tahir Aleem e Shaojun Long. "Prenyl Transferases Regulate Secretory Protein Sorting and Parasite Morphology in Toxoplasma gondii". International Journal of Molecular Sciences 24, n. 8 (12 aprile 2023): 7172. http://dx.doi.org/10.3390/ijms24087172.
Testo completoAbstract (sommario):
Protein prenylation is an important protein modification that is responsible for diverse physiological activities in eukaryotic cells. This modification is generally catalyzed by three types of prenyl transferases, which include farnesyl transferase (FT), geranylgeranyl transferase (GGT-1) and Rab geranylgeranyl transferase (GGT-2). Studies in malaria parasites showed that these parasites contain prenylated proteins, which are proposed to play multiple functions in parasites. However, the prenyl transferases have not been functionally characterized in parasites of subphylum Apicomplexa. Here, we functionally dissected functions of three of the prenyl transferases in the Apicomplexa model organism Toxoplasma gondii (T. gondii) using a plant auxin-inducible degron system. The homologous genes of the beta subunit of FT, GGT-1 and GGT-2 were endogenously tagged with AID at the C-terminus in the TIR1 parental line using a CRISPR-Cas9 approach. Upon depletion of these prenyl transferases, GGT-1 and GGT-2 had a strong defect on parasite replication. Fluorescent assay using diverse protein markers showed that the protein markers ROP5 and GRA7 were diffused in the parasites depleted with GGT-1 and GGT-2, while the mitochondrion was strongly affected in parasites depleted with GGT-1. Importantly, depletion of GGT-2 caused the stronger defect to the sorting of rhoptry protein and the parasite morphology. Furthermore, parasite motility was observed to be affected in parasites depleted with GGT-2. Taken together, this study functionally characterized the prenyl transferases, which contributed to an overall understanding of protein prenylation in T. gondii and potentially in other related parasites.
10
Charrier, Cédric, Gary J. Duncan, Martin D. Reid, Garry J. Rucklidge, Donna Henderson, Pauline Young, Valerie J. Russell, Rustam I. Aminov, Harry J. Flint e Petra Louis. "A novel class of CoA-transferase involved in short-chain fatty acid metabolism in butyrate-producing human colonic bacteria". Microbiology 152, n. 1 (1 gennaio 2006): 179–85. http://dx.doi.org/10.1099/mic.0.28412-0.
Testo completoAbstract (sommario):
Bacterial butyryl-CoA CoA-transferase activity plays a key role in butyrate formation in the human colon, but the enzyme and corresponding gene responsible for this activity have not previously been identified. A novel CoA-transferase gene is described from the colonic bacterium Roseburia sp. A2-183, with similarity to acetyl-CoA hydrolase as well as 4-hydroxybutyrate CoA-transferase sequences. The gene product, overexpressed in an Escherichia coli lysate, showed activity with butyryl-CoA and to a lesser degree propionyl-CoA in the presence of acetate. Butyrate, propionate, isobutyrate and valerate competed with acetate as the co-substrate. Despite the sequence similarity to 4-hydroxybutyrate CoA-transferases, 4-hydroxybutyrate did not compete with acetate as the co-substrate. Thus the CoA-transferase preferentially uses butyryl-CoA as substrate. Similar genes were identified in other butyrate-producing human gut bacteria from clostridial clusters IV and XIVa, while other candidate CoA-transferases for butyrate formation could not be detected in Roseburia sp. A2-183. This suggests strongly that the newly identified group of CoA-transferases described here plays a key role in butyrate formation in the human colon.
11
Guthenberg, C., H. Jensson, L. Nyström, E. Österlund, M. K. Tahir e B. Mannervik. "Isoenzymes of glutathione transferase in rat kidney cytosol". Biochemical Journal 230, n. 3 (15 settembre 1985): 609–15. http://dx.doi.org/10.1042/bj2300609.
Testo completoAbstract (sommario):
Glutathione transferases from rat kidney cytosol were purified about 40-fold by chromatography on S-hexylglutathione linked to epoxy-activated Sepharose 6B. Further purification by fast protein liquid chromatography with chromatofocusing in the pH interval 10.6-7.6 resolved five major peaks of activity with 1-chloro-2,4-dinitrobenzene as the second substrate. Four of the peaks were identified with rat liver transferases 1-1, 1-2, 2-2 and 4-4 respectively. The criteria used for identification included physical properties, reactions with specific antibodies, substrate specificities and sensitivities to several inhibitors. The fourth major peak is a ‘new’ form of transferase, which has not been found in rat liver. This isoenzyme, glutathione transferase 7-7, has a lower apparent subunit Mr than any of the transferases isolated from rat liver cytosol, and does not react with antibodies raised against the liver enzymes. Glutathione transferases 3-3 and 3-4, which are abundant in liver, were only present in very small amounts. In a separate chromatofocusing separation in a lower pH interval, an additional peak was eluted at pH 6.3. This isoenzyme is characterized by its high activity with ethacrynic acid.
12
Muhammad Mohiuddin Alamgir, Qamar Jamal e Talat Mirza. "Gene-gene and gene-environment interaction: an important predictor of oral cancer among smokeless tobacco users in Karachi". Journal of the Pakistan Medical Association 72, n. 3 (3 marzo 2022): 477–82. http://dx.doi.org/10.47391/jpma.1806.
Testo completoAbstract (sommario):
Objective: To determine the risk for oral cancer caused by simultaneous occurrence of more than one of the tested cytochrome P450 1A1MspI, glutathione S-transferaseM1 null gnd Glutathione S-transferasesT1 null gene polymorphisms. Method: The cross-sectional case-control study was conducted from December 2011 to October 2016 at the Ziauddin University, Karachi, in collaboration with Dow University of Health Sciences, Karachi, and comprised oral squamous cell carcinoma cases in group A and healthy tobacco habit-matched controls in group B. All investigations were done using standardised laboratory protocols. The outcomes were determined in terms of association of various combinations of cytochrome P450 1A1MspI, glutathione S-transferasesM1 null and glutathione S-transferases T1 null polymorphisms with oral cancer. Data was analysed using SPSS 20. Results: Of the 238 subjects, 140(58.8%) were in group A and 98(41.2%) were in group B. Mean ages in group A and B were 47.1±12.22 and 41.6±14.58 years, respectively. Male/Female ratio in group A was 1.88:1 while 83.4% were using tobacco. When cytochrome P450 1A1MspI homozygous (m2/m2) and glutathione S-transferasesM1 null variants occured simultaneously in an individual, an odds ratio of 12.8 (95% confidence interval: 1.20-135.5; p=0.03) among overall tobacco chewers was observed. For glutathione S-transferasesM1 not null and glutathione S-transferasesT1 null variant combination among overall tobacco users, the conferred odds ratio was 4.58 (95% confidence interval: 0.99-21.2; p=0.05). The other studied gene combinations did not reveal significant associations (p>0.05). ---Continue
13
Pollock, Thomas J., Wilbert A. T. van Workum, Linda Thorne, Marcia J. Mikolajczak, Motohide Yamazaki, Jan W. Kijne e Richard W. Armentrout. "Assignment of Biochemical Functions to Glycosyl Transferase Genes Which Are Essential for Biosynthesis of Exopolysaccharides in Sphingomonas Strain S88 andRhizobium leguminosarum". Journal of Bacteriology 180, n. 3 (1 febbraio 1998): 586–93. http://dx.doi.org/10.1128/jb.180.3.586-593.1998.
Testo completoAbstract (sommario):
ABSTRACT Glycosyl transferases which recognize identical substrates (nucleotide-sugars and lipid-linked carbohydrates) can substitute for one another in bacterial polysaccharide biosynthesis, even if the enzymes originate in different genera of bacteria. This substitution can be used to identify the substrate specificities of uncharacterized transferase genes. The spsK gene ofSphingomonas strain S88 and the pssDE genes ofRhizobium leguminosarum were identified as encoding glucuronosyl-(β1→4)-glucosyl transferases based on reciprocal genetic complementation of mutations in the spsK gene and the pssDE genes by segments of cloned DNA and by the SpsK-dependent incorporation of radioactive glucose (Glc) and glucuronic acid (GlcA) into lipid-linked disaccharides in EDTA-permeabilized cells. By contrast, glycosyl transferases which form alternative sugar linkages to the same substrate caused inhibition of polysaccharide synthesis or were deleterious or lethal in a foreign host. The negative effects also suggested specific substrate requirements: we propose that spsL codes for a glucosyl-(β1→4)-glucuronosyl transferase inSphingomonas and that pssC codes for a glucuronosyl-(β1→4)-glucuronosyl transferase in R. leguminosarum. Finally, the complementation results indicate the order of attachment of sphingan main-chain sugars to the C55-isoprenylphosphate carrier as -Glc-GlcA-Glc-isoprenylpyrophosphate.
14
Ali, Nahla Osman Mohamed. "Bioinformatical Analysis of HGPRT Transferase from Different Malaria Parasite Plasmodium spp. Using Computational Tools". Malaysian Journal of Medical and Biological Research 4, n. 2 (31 dicembre 2017): 85–90. http://dx.doi.org/10.18034/mjmbr.v4i2.430.
Testo completoAbstract (sommario):
In this study, HGPRT transferases from different malaria parasite Plasmodium species was analyzed and presented in this communication. The composition of leucine, lysine and Isoleucine were the highest while lowest concentrations of tryptophan and glutamine residues were noticed when compared to other amino acids. pI value of P. reichenowi HGPRT was 7.59 while the lowest pI of 6.22 was shown by P. chabaudi HGPRT. The instability index of all the transferases is varied, but for all of them it was less than 40, which indicates that all of them are stable. The aliphatic index was found to span within a range of 83 to 97. Secondary structural analysis of the transferases showed the pre-dominance of random coils followed by extended strands for all the transferases except P. falciparum, P. Knowlesi and P. reichenowi HGPRT transferase. The significance of the above results is discussed in the light of existing literature.
15
Hsiao, C. D., E. O. Martsen, J. Y. Lee, S. P. Tsai e M. F. Tam. "Amino acid sequencing, molecular cloning and modelling of the chick liver class-theta glutathione S-transferase CL1". Biochemical Journal 312, n. 1 (15 novembre 1995): 91–98. http://dx.doi.org/10.1042/bj3120091.
Testo completoAbstract (sommario):
Glutathione S-transferase CL1-2 heterodimers purified from 1-day-old chick livers were digested with Achromobacter proteinase I. The resulting fragments were separated for amino acid sequence analysis. Oligonucleotide probes were constructed based on sequence similarity to class-Theta glutathione S-transferases for PCR using a chicken liver cDNA library as template. A full-length clone (1725 bp) encoding a polypeptide comprising 261 amino acids was isolated. Including conservative substitutions, this protein has 70-73% sequence similarity with other mammalian class-Theta glutathione S-transferases. Based on known X-ray crystal structures of class-Alpha, -Mu and -Pi glutathione S-transferases, a model is constructed for the N-terminal 232 residues of CL1.
16
Brophy, P. M., C. Southan e J. Barrett. "Glutathione transferases in the tapeworm Moniezia expansa". Biochemical Journal 262, n. 3 (15 settembre 1989): 939–46. http://dx.doi.org/10.1042/bj2620939.
Testo completoAbstract (sommario):
Four forms of GSH transferase were resolved from Moniezia expansa cytosol by GSH-Sepharose affinity chromatography and chromatofocusing in the range pH 6-4, and the presence of isoenzymes was further suggested by analytical isoelectric focusing. The four GSH transferase forms in the cestode showed no clear biochemical relationship to any one mammalian GSH transferase family. The N-terminal of the major GSH transferase form showed sequence homology with the Mu and Alpha family GSH transferases. The major GSH transferase appeared to bind a number of commercially available anthelmintics but did not appear to conjugate the compounds with GSH. The major GSH transferase efficiently conjugated members of the trans-alk-2-enal and trans, trans-alka-2,4-dienal series, established secondary products of lipid peroxidation.
17
Benson, A. M., M. J. Hunkeler e J. L. York. "Mouse hepatic glutathione transferase isoenzymes and their differential induction by anticarcinogens. Specificities of butylated hydroxyanisole and bisethylxanthogen as inducers of glutathione transferases in male and female CD-1 mice". Biochemical Journal 261, n. 3 (1 agosto 1989): 1023–29. http://dx.doi.org/10.1042/bj2611023.
Testo completoAbstract (sommario):
GSH transferase isoenzymes of class Mu (two forms), class Pi (one form) and class Alpha (two forms) were purified from liver cytosols of female CD-1 mice pretreated with an anticarcinogenic inducer, 2(3)-t-butyl-4-hydroxyanisole. GSH transferases GT-8.7, GT-8.8a and GT-8.8b, GT-9.0, GT-9.3, GT-10.3 and GT-10.6 contained a minimum of six types of subunits distinguishable by structural, catalytic and immunological characteristics. H.p.l.c. analysis of the subunit compositions of affinity-purified GSH transferases from liver cytosols of induced and non-induced male and female CD-1 mice showed that two anticarcinogenic compounds, 2(3)-t-butyl-4-hydroxyanisole and bisethylxanthogen, differed markedly in their specificities as inducers of GSH transferase.
18
Hayes, J. D., e T. J. Mantle. "Inhibition of hepatic and extrahepatic glutathione S-transferases by primary and secondary bile acids". Biochemical Journal 233, n. 2 (15 gennaio 1986): 407–15. http://dx.doi.org/10.1042/bj2330407.
Testo completoAbstract (sommario):
Glutathione S-transferases are a complex family of dimeric proteins that play a dual role in cellular detoxification; they catalyse the first step in the synthesis of mercapturic acids, and they bind potentially harmful non-substrate ligands. Bile acids are quantitatively the major group of ligands encountered by the glutathione S-transferases. The enzymes from rat liver comprise Yk (Mr 25 000), Ya (Mr 25 500), Yn (Mr 26 500), Yb1, Yb2 (both Mr 27 000) and Yc (Mr 28 500) monomers. Although bile acids inhibited the catalytic activity of all transferases studied, the concentration of a particular bile acid required to produce 50% inhibition (I50) varies considerably. A comparison of the I50 values obtained with lithocholate (monohydroxylated), chenodeoxycholate (dihydroxylated) and cholate (trihydroxylated) showed that, in contrast with all other transferase monomers, the Ya subunit possesses a relatively hydrophobic bile-acid-binding site. The I50 values obtained with lithocholate and lithocholate 3-sulphate showed that only the Ya subunit is inhibited more effectively by lithocholate than by its sulphate ester. Other subunits (Yk, Yn, Yb1 and Yb2) were inhibited more by lithocholate 3-sulphate than by lithocholate, indicating the existence of a significant ionic interaction, in the bile-acid-binding domain, between (an) amino acid residue(s) and the steroid ring A. By contrast, increasing the assay pH from 6.0 to 7.5 decreased the inhibitory effect of all bile acids studied, suggesting that there is little significant ionic interaction between transferase subunits and the carboxy group of bile acids. Under alkaline conditions, low concentrations (sub-micellar) of nonsulphated bile acids activated Yb1, Yb2 and Yc subunits but not Yk, Ya and Yn subunits. The diverse effects of the various bile acids studied on transferase activity enables these ligands to be used to help establish the quaternary structure of individual enzymes. Since these inhibitors can discriminate between transferases that appear to be immunochemically identical (e.g. transferases F and L), bile acids can provide information about the subunit composition of forms that cannot otherwise be distinguished.
19
Danielson, U. H., e B. Mannervik. "Paradoxical inhibition of rat glutathione transferase 4-4 by indomethacin explained by substrate-inhibitor-enzyme complexes in a random-order sequential mechanism". Biochemical Journal 250, n. 3 (15 marzo 1988): 705–11. http://dx.doi.org/10.1042/bj2500705.
Testo completoAbstract (sommario):
Under standard assay conditions, with 1-chloro-2,4-dinitrobenzene (CDNB) as electrophilic substrate, rat glutathione transferase 4-4 is strongly inhibited (I50 = 1 microM) by indomethacin. No other glutathione transferase investigated is significantly inhibited by micromolar concentrations of indomethacin. Paradoxically, the strong inhibition of glutathione transferase 4-4 was dependent on high (millimolar) concentrations of CDNB; at low concentrations of this substrate or with other substrates the effect of indomethacin on the enzyme was similar to the moderate inhibition noted for other glutathione transferases. In general, the inhibition of glutathione transferases can be explained by a random-order sequential mechanism, in which indomethacin acts as a competitive inhibitor with respect to the electrophilic substrate. In the specific case of glutathione transferase 4-4 with CDNB as substrate, indomethacin binds to enzyme-CDNB and enzyme-CDNB-GSH complexes with an even greater affinity than to the corresponding complexes lacking CDNB. Under presumed physiological conditions with low concentrations of electrophilic substrates, indomethacin is not specific for glutathione transferase 4-4 and may inhibit all forms of glutathione transferase.
20
Beláňová, Martina, Petronela Dianišková, Patrick J. Brennan, Gladys C. Completo, Natisha L. Rose, Todd L. Lowary e Katarína Mikušová. "Galactosyl Transferases in Mycobacterial Cell Wall Synthesis". Journal of Bacteriology 190, n. 3 (30 novembre 2007): 1141–45. http://dx.doi.org/10.1128/jb.01326-07.
Testo completoAbstract (sommario):
ABSTRACT Two galactosyl transferases can apparently account for the full biosynthesis of the cell wall galactan of mycobacteria. Evidence is presented based on enzymatic incubations with purified natural and synthetic galactofuranose (Galf) acceptors that the recombinant galactofuranosyl transferase, GlfT1, from Mycobacterium smegmatis, the Mycobacterium tuberculosis Rv3782 ortholog known to be involved in the initial steps of galactan formation, harbors dual β-(1→4) and β-(1→5) Galf transferase activities and that the product of the enzyme, decaprenyl-P-P-GlcNAc-Rha-Galf-Galf, serves as a direct substrate for full polymerization catalyzed by another bifunctional Galf transferase, GlfT2, the Rv3808c enzyme.
21
Williams, Ernest, Tsvetan Bachvaroff e Allen Place. "A Comparison of Dinoflagellate Thiolation Domain Binding Proteins Using In Vitro and Molecular Methods". Marine Drugs 20, n. 9 (18 settembre 2022): 581. http://dx.doi.org/10.3390/md20090581.
Testo completoAbstract (sommario):
Dinoflagellates play important roles in ecosystems as primary producers and consumers making natural products that can benefit or harm environmental and human health but are also potential therapeutics with unique chemistries. Annotations of dinoflagellate genes have been hampered by large genomes with many gene copies that reduce the reliability of transcriptomics, quantitative PCR, and targeted knockouts. This study aimed to functionally characterize dinoflagellate proteins by testing their interactions through in vitro assays. Specifically, nine Amphidinium carterae thiolation domains that scaffold natural product synthesis were substituted into an indigoidine synthesizing gene from the bacterium Streptomyces lavendulae and exposed to three A. carterae phosphopantetheinyl transferases that activate synthesis. Unsurprisingly, several of the dinoflagellate versions inhibited the ability to synthesize indigoidine despite being successfully phosphopantetheinated. However, all the transferases were able to phosphopantetheinate all the thiolation domains nearly equally, defying the canon that transferases participate in segregated processes via binding specificity. Moreover, two of the transferases were expressed during growth in alternating patterns while the final transferase was only observed as a breakdown product common to all three. The broad substrate recognition and compensatory expression shown here help explain why phosphopantetheinyl transferases are lost throughout dinoflagellate evolution without a loss in a biochemical process.
22
Leutwein, Christina, e Johann Heider. "Succinyl-CoA:(R)-Benzylsuccinate CoA-Transferase: an Enzyme of the Anaerobic Toluene Catabolic Pathway in Denitrifying Bacteria". Journal of Bacteriology 183, n. 14 (15 luglio 2001): 4288–95. http://dx.doi.org/10.1128/jb.183.14.4288-4295.2001.
Testo completoAbstract (sommario):
ABSTRACT Anaerobic microbial toluene catabolism is initiated by addition of fumarate to the methyl group of toluene, yielding (R)-benzylsuccinate as first intermediate, which is further metabolized via β-oxidation to benzoyl-coenzyme A (CoA) and succinyl-CoA. A specific succinyl-CoA:(R)-benzylsuccinate CoA-transferase activating (R)-benzylsuccinate to the CoA-thioester was purified and characterized from Thauera aromatica. The enzyme is fully reversible and forms exclusively the 2-(R)-benzylsuccinyl-CoA isomer. Only some close chemical analogs of the substrates are accepted by the enzyme: succinate was partially replaced by maleate or methylsuccinate, and (R)-benzylsuccinate was replaced by methylsuccinate, benzylmalonate, or phenylsuccinate. In contrast to all other known CoA-transferases, the enzyme consists of two subunits of similar amino acid sequences and similar sizes (44 and 45 kDa) in an α2β2 conformation. Identity of the subunits with the products of the previously identified toluene-inducedbbsEF genes was confirmed by determination of the exact masses via electrospray-mass spectrometry. The deduced amino acid sequences resemble those of only two other characterized CoA-transferases, oxalyl-CoA:formate CoA-transferase and (E)-cinnamoyl-CoA:(R)-phenyllactate CoA-transferase, which represent a new family of CoA-transferases. As suggested by kinetic analysis, the reaction mechanism of enzymes of this family apparently involves formation of a ternary complex between the enzyme and the two substrates.
23
Garcerá, Ana, Lina Barreto, Lidia Piedrafita, Jordi Tamarit e Enrique Herrero. "Saccharomyces cerevisiae cells have three Omega class glutathione S-transferases acting as 1-Cys thiol transferases". Biochemical Journal 398, n. 2 (15 agosto 2006): 187–96. http://dx.doi.org/10.1042/bj20060034.
Testo completoAbstract (sommario):
The Saccharomyces cerevisiae genome encodes three proteins that display similarities with human GSTOs (Omega class glutathione S-transferases) hGSTO1-1 and hGSTO2-2. The three yeast proteins have been named Gto1, Gto2 and Gto3, and their purified recombinant forms are active as thiol transferases (glutaredoxins) against HED (β-hydroxyethyl disulphide), as dehydroascorbate reductases and as dimethylarsinic acid reductases, while they are not active against the standard GST substrate CDNB (1-chloro-2,4-dinitrobenzene). Their glutaredoxin activity is also detectable in yeast cell extracts. The enzyme activity characteristics of the Gto proteins contrast with those of another yeast GST, Gtt1. The latter is active against CDNB and also displays glutathione peroxidase activity against organic hydroperoxides such as cumene hydroperoxide, but is not active as a thiol transferase. Analysis of point mutants derived from wild-type Gto2 indicates that, among the three cysteine residues of the molecule, only the residue at position 46 is required for the glutaredoxin activity. This indicates that the thiol transferase acts through a monothiol mechanism. Replacing the active site of the yeast monothiol glutaredoxin Grx5 with the proposed Gto2 active site containing Cys46 allows Grx5 to retain some activity against HED. Therefore the residues adjacent to the respective active cysteine residues in Gto2 and Grx5 are important determinants for the thiol transferase activity against small disulphide-containing molecules.
24
Danielson, U. H., e B. Mannervik. "Kinetic independence of the subunits of cytosolic glutathione transferase from the rat". Biochemical Journal 231, n. 2 (15 ottobre 1985): 263–67. http://dx.doi.org/10.1042/bj2310263.
Testo completoAbstract (sommario):
The steady-state kinetics of the dimeric glutathione transferases deviate from Michaelis-Menten kinetics, but have hyperbolic binding isotherms for substrates and products of the enzymic reaction. The possibility of subunit interactions during catalysis as an explanation for the rate behaviour was investigated by use of rat isoenzymes composed of subunits 1, 2, 3 and 4, which have distinct substrate specificities. The kinetic parameter kcat./Km was determined with 1-chloro-2,4-dinitrobenzene, 4-hydroxyalk-2-enals, ethacrynic acid and trans-4-phenylbut-3-en-2-one as electrophilic substrates for six isoenzymes: rat glutathione transferases 1-1, 1-2, 2-2, 3-3, 3-4 and 4-4. It was found that the kcat./Km values for the heterodimeric transferases 1-2 and 3-4 could be predicted from the kcat./Km values of the corresponding homodimers. Likewise, the initial velocities determined with transferases 3-3, 3-4 and 4-4 at different degrees of saturation with glutathione and 1-chloro-2,4-dinitrobenzene demonstrated that the kinetic properties of the subunits are additive. These results show that the subunits of glutathione transferase are kinetically independent.
25
Gerken, Thomas A., Jiexin Zhang, Jessica Levine e Åke Elhammer. "Mucin CoreO-Glycosylation Is Modulated by Neighboring Residue Glycosylation Status". Journal of Biological Chemistry 277, n. 51 (22 ottobre 2002): 49850–62. http://dx.doi.org/10.1074/jbc.m205851200.
Testo completoAbstract (sommario):
The influence of peptide sequence and environment on the initiation and elongation of mucinO-glycosylation is not well understood. Thein vivoglycosylation pattern of the porcine submaxillary gland mucin (PSM) tandem repeat containing 31O-glycosylation sites (Gerken, T. A., Gilmore, M., and Zhang, J. (2002)J. Biol. Chem.277, 7736–7751) reveals a weak inverse correlation with hydroxyamino acid density (and by inference the density of glycosylation) with the extent of GalNAc glycosylation and core-1 substitution. We now report the time course of thein vitroglycosylation of the apoPSM tandem repeat by recombinant UDP-GalNAc:polypeptide α-GalNAc transferases (ppGalNAc transferase) T1 and T2 that confirm these findings. A wide range of glycosylation rates are found, with several residues showing apparent plateaus in glycosylation. An adjustable kinetic model that reduces the first-order rate constants proportional to neighboring glycosylation status, plus or minus three residues of the site of glycosylation, was found to reasonably reproduce the experimental rate data for both transferases, including apparent plateaus in glycosylation. The unique, transferase-specific, positional weighting constants reveal information on the peptide/glycopeptide recognition site for each transferase. Both transferases displayed high sensitivities to neighboring Ser/Thr glycosylation, whereas ppGalNAc T2 displayed additional high sensitivities to the presence of nonglycosylated Ser/Thr residues. This is the first demonstration of the ability to model mucinO-glycosylation kinetics, confirming that under the appropriate conditions neighboring glycosylation status can be a significant factor modulating the first step of mucinO-glycan biosynthesis.
26
Anderson, K., R. Andrews, L. Yin, R. McLeod, C. MacDonald, J. D. Hayes e M. H. Grant. "Cytotoxicity of xenobiotics and expression of glutathione-S-transferases in immortalised rat hepatocyte cell lines". Human & Experimental Toxicology 17, n. 3 (marzo 1998): 131–37. http://dx.doi.org/10.1177/096032719801700301.
Testo completoAbstract (sommario):
1 Immortalised rat hepatocyte cell lines are more sensitive to the cytotoxicity of 1-chloro-2,4-dinitroben-zene and ethacrynic acid than primary cultures of hepatocytes. 2 Class alpha glutathione S-transferases are not expressed in immortalised hepatocyte cell lines. Class pi glutathione S-transferase expression is elevated in the immortalised cell lines compared with freshly isolated hepatocytes, but it is not as high as in the HTC rat hepatoma cell line. 3 Immortalised hepatocyte cell lines may provide a sensitive model system for detecting cytotoxicity associated with xenobiotics which are detoxified by glutathione S-transferases.
27
Theodore, C., S. V. Singh, T. D. Hong e Y. C. Awasthi. "Glutathione S-transferases of human brain. Evidence for two immunologically distinct types of 26500-Mr subunits". Biochemical Journal 225, n. 2 (15 gennaio 1985): 375–82. http://dx.doi.org/10.1042/bj2250375.
Testo completoAbstract (sommario):
Human brain contains one cationic (pI8.3) and two anionic (pI5.5 and 4.6) forms of glutathione S-transferase. The cationic form (pI8.3) and the less-anionic form (pI5.5) do not correspond to any of the glutathione S-transferases previously characterized in human tissues. Both of these forms are dimers of 26500-Mr subunits; however, immunological and catalytic properties indicate that these two enzyme forms are different from each other. The cationic form (pI8.3) cross-reacts with antibodies raised against cationic glutathione S-transferases of human liver, whereas the anionic form (pI5.5) does not. Additionally, only the cationic form expresses glutathione peroxidase activity. The other anionic form (pI4.6) is a dimer of 24500-Mr and 22500-Mr subunits. Two-dimensional gel electrophoresis demonstrates that there are three types of 26500-Mr subunits, two types of 24500-Mr subunits and two types of 22500-Mr subunits present in the glutathione S-transferases of human brain.
28
Tahir, M. K., N. Ozer e B. Mannervik. "Isoenzymes of glutathione transferase in rat small intestine". Biochemical Journal 253, n. 3 (1 agosto 1988): 759–64. http://dx.doi.org/10.1042/bj2530759.
Testo completoAbstract (sommario):
The major glutathione transferases in the rat small-intestine cytosol were isolated and characterized. The enzymes active with 1-chloro-2,4-dinitrobenzene as second substrate were almost quantitatively recovered after affinity chromatography on immobilized S-hexylglutathione. The different basic forms of glutathione transferase, which account for 90% of the activity, were resolved by chromatofocusing. Fractions containing enzymes with lower isoelectric points were not further resolved. The isolated fractions were characterized by their elution position in chromatofocusing, apparent subunit Mr, reactions with specific antibodies, substrate specificities and inhibition characteristics. The major basic forms identified were glutathione transferases 1-1, 4-4 and 7-7. In addition, evidence for the presence of a variant form of subunit 1, as well as trace amounts of subunits 2 and 3, was obtained. A significant amount of transferase 8-8 in the fraction of acidic enzyme forms was demonstrated by immunoblot and Ouchterlony double-diffusion analysis. In the comparison of the occurrence of the different forms of glutathione transferase in liver, lung, kidney and small intestine, it was found that the small intestine is the richest source of glutathione transferase 7-7.
29
Schecter, Robyn L., Moulay A. Alaoui-Jamali e Gerald Batist. "Glutathione S-transferase in chemotherapy resistance and in carcinogenesis". Biochemistry and Cell Biology 70, n. 5 (1 maggio 1992): 349–53. http://dx.doi.org/10.1139/o92-054.
Testo completoAbstract (sommario):
Cytosolic glutathione S-transferases are composed of two monomeric subunits. These monomers are the products of different gene families designated alpha, mu, and pi. Dimerization yields either homodimeric or heterodimeric holoenzymes within the same family. The members of this complex group of proteins have been linked to the detoxification of environmental chemicals and carcinogens, and have been shown to be overexpressed in normal and tumor cells following exposure to cytotoxic drugs. They also are overexpressed in carcinogen-induced rat liver preneoplastic nodules in rat liver. In all of these cases, the changes in exprssion of glutathione S-transferases are paralleled by increased resistance to cytotoxic chemicals. The degree of resistance is related to the substrate specificity of the isozyme. The relationship of the glutathione S-transferase genes to drug resistance has been directly demonstrated by gene transfer studies, where cDNAs encoding the various subunits of glutathione S-transferase have been transfected into a variety of cell types. This review discusses the results of numerous studies that associate resistance to alkylating agents with overexpression of protective detoxifying glutathione S-transferase enzymes.Key words: glutathione S-transferase, chemotherapy, carcinogenesis, alkylating agents, DNA damage.
30
Söderström, M., S. Hammarström e B. Mannervik. "Leukotriene C synthase in mouse mastocytoma cells. An enzyme distinct from cytosolic and microsomal glutathione transferases". Biochemical Journal 250, n. 3 (15 marzo 1988): 713–18. http://dx.doi.org/10.1042/bj2500713.
Testo completoAbstract (sommario):
Leukotriene C4 synthesis was studied in preparations from mouse mastocytoma cells. Enzymic conjugation of leukotriene A4 with glutathione was catalysed by both the cytosol and the microsomal fraction. The specific activity of the microsomal fraction (7.8 nmol/min per mg of protein) was 17 times that of the cytosol fraction. The cytosol fraction of the mastocytoma cells contained two glutathione transferases, which were purified to homogeneity and characterized. A microsomal glutathione transferase was purified from mouse liver; this enzyme was shown by immunoblot analysis to be present in the mastocytoma microsomal fraction at a concentration one-tenth or less of that in the liver microsomal fraction. Both the cytosolic and the microsomal glutathione transferases in the mastocytoma cells were identified with enzymes previously characterized, by determining specific activities with various substrates, sensitivities to inhibitors, reactions with antibodies, and physical properties. The purified microsomal glutathione transferase from liver was inactive with leukotriene A4 or its methyl ester as substrate. The cytosolic enzymes displayed activity with leukotriene A4, but their specific activities and intracellular concentrations were too low to account for the leukotriene C4 formation in the mastocytoma cells. The microsomal fraction of the cells contained an enzyme distinguishable by various criteria from the previously studied glutathione transferases. This membrane-bound enzyme, leukotriene C synthase (leukotriene A4:glutathione S-leukotrienyltransferase), appears to carry the main responsibility for the biosynthesis of leukotriene C4.
31
Dixon, David P., e Robert Edwards. "Glutathione Transferases". Arabidopsis Book 8 (gennaio 2010): e0131. http://dx.doi.org/10.1199/tab.0131.
Testo completo
32
Hayes, John D., Jack U. Flanagan e Ian R. Jowsey. "GLUTATHIONE TRANSFERASES". Annual Review of Pharmacology and Toxicology 45, n. 1 (22 settembre 2005): 51–88. http://dx.doi.org/10.1146/annurev.pharmtox.45.120403.095857.
Testo completoAbstract (sommario):
This review describes the three mammalian glutathione transferase (GST) families, namely cytosolic, mitochondrial, and microsomal GST, the latter now designated MAPEG. Besides detoxifying electrophilic xenobiotics, such as chemical carcinogens, environmental pollutants, and antitumor agents, these transferases inactivate endogenous α,β-unsaturated aldehydes, quinones, epoxides, and hydroperoxides formed as secondary metabolites during oxidative stress. These enzymes are also intimately involved in the biosynthesis of leukotrienes, prostaglandins, testosterone, and progesterone, as well as the degradation of tyrosine. Among their substrates, GSTs conjugate the signaling molecules 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) and 4-hydroxynonenal with glutathione, and consequently they antagonize expression of genes trans-activated by the peroxisome proliferator-activated receptor γ (PPARγ) and nuclear factor-erythroid 2 p45-related factor 2 (Nrf2). Through metabolism of 15d-PGJ2, GST may enhance gene expression driven by nuclear factor-κB (NF-κB). Cytosolic human GST exhibit genetic polymorphisms and this variation can increase susceptibility to carcinogenesis and inflammatory disease. Polymorphisms in human MAPEG are associated with alterations in lung function and increased risk of myocardial infarction and stroke. Targeted disruption of murine genes has demonstrated that cytosolic GST isoenzymes are broadly cytoprotective, whereas MAPEG proteins have proinflammatory activities. Furthermore, knockout of mouse GSTA4 and GSTZ1 leads to overexpression of transferases in the Alpha, Mu, and Pi classes, an observation suggesting they are part of an adaptive mechanism that responds to endogenous chemical cues such as 4-hydroxynonenal and tyrosine degradation products. Consistent with this hypothesis, the promoters of cytosolic GST and MAPEG genes contain antioxidant response elements through which they are transcriptionally activated during exposure to Michael reaction acceptors and oxidative stress.
33
Boyer, T. D., e W. C. Kenney. "Acidic glutathione S-transferases of rat testis". Biochemical Journal 230, n. 1 (15 agosto 1985): 125–32. http://dx.doi.org/10.1042/bj2300125.
Testo completoAbstract (sommario):
In most organs of the rat the predominant forms of glutathione S-transferase have alkaline (greater than 7.0) pI values. In contrast, in the cytosol from rat testes almost 50% of the transferase activity is due to isoenzymes with acidic (less than 7.0) pI values. We have purified three acidic forms of glutathione S-transferase from rat testis cytosol. One form accounted for more than 90% of the enzymic activity in the acidic fraction. This major form was a homodimer of a new subunit, termed Yt. This subunit had an electrophoretic mobility that was different from the subunits that form the alkaline transferases. In addition, functional and immunological studies were consistent with the unique nature of the Yt subunit. The two minor acidic enzymes of rat testis appeared to be heterodimers of the Yt subunit and a subunit with an electrophoretic mobility identical with that of the Yb subunit present in some alkaline enzymes.
34
MEYER, David J., Richmond MUIMO, Michael THOMAS, David COATES e R. Elwyn ISAAC. "Purification and characterization of prostaglandin-H E-isomerase, a sigma-class glutathione S-transferase, from Ascaridia galli". Biochemical Journal 313, n. 1 (1 gennaio 1996): 223–27. http://dx.doi.org/10.1042/bj3130223.
Testo completoAbstract (sommario):
Comparison of partial primary sequences of sigma-class glutathione S-transferases (GSH) of parasitic helminths and a GSH-dependent prostaglandin (PG)-H D-isomerase of rat immune accessory cells suggested that some of the helminth enzymes may also be involved in PG biosynthesis [Meyer and Thomas (1995) Biochem. J. 311, 739-742]. A soluble GSH transferase of the parasitic nematode Ascaridia galli has now been purified which shows high activity and specificity in the GSH-dependent isomerization of PGH to PGE, comparable to that of the rat spleen enzyme in its isomerization of PGH to PGD, and similarly stimulates the activity of prostaglandin H synthase. The enzyme subunit is structurally related to the rat spleen enzyme and sigma-class GSH transferases of helminths according to the partial primary sequence. The data support the hypothesis that some sigma-class GSH transferases of helminth parasites are involved in PG biosynthesis which, in the case of PGE, is likely to be associated with the subversion or suppression of host immunity. A PG-H E-isomerase of comparable specificity and activity has not previously been isolated.
35
Hayes, J. D. "Purification and physical characterization of glutathione S-transferase K. Differential use of S-hexylglutathione and glutathione affinity matrices to isolate a novel glutathione S-transferase from rat liver". Biochemical Journal 233, n. 3 (1 febbraio 1986): 789–98. http://dx.doi.org/10.1042/bj2330789.
Testo completoAbstract (sommario):
A novel hepatic enzyme, glutathione S-transferase K, is described that, unlike previously characterized transferases, possesses little affinity for S-hexylglutathione-Sepharose 6B but can be isolated because it binds to a glutathione affinity matrix. A purification scheme for this new enzyme was devised, with the use of DEAE-cellulose, S-hexylglutathione-Sepharose 6B, glutathione-Sepharose 6B and hydroxyapatite chromatography. The final hydroxyapatite step results in the elution of three chromatographically interconvertible forms, K1, K2 and K3. The purified protein has an isoelectric point of 6.1 and comprises subunits that are designated Yk (Mr 25,000); during sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, it migrates marginally faster than the Ya subunit but slower than the pulmonary Yf monomer (Mr 24,500). Transferase K displays catalytic, immunochemical and physical properties that are distinct from those of other liver transferases. Tryptic peptide maps suggest that transferase K is a homodimer, or comprises closely homologous subunits. The tryptic fingerprints also demonstrate that, although transferase K is structurally separate from previously described hepatic forms, a limited sequence homology exists between the Yk, Ya and Yc polypeptides. These structural data are in accord with the immunochemical results presented in the accompanying paper [Hayes & Mantle (1986) Biochem. J. 233, 779-788].
36
Tang, Fang, Xiu-Bo Zhang, Yu-Sheng Liu e Xi-Wu Gao. "Tissue Distribution and Properties of Glutathione S-transferases in Micromelalopha troglodyta (Lepidoptera: Notodontidae)". Journal of Entomological Science 43, n. 3 (1 luglio 2008): 268–78. http://dx.doi.org/10.18474/0749-8004-43.3.268.
Testo completoAbstract (sommario):
The small prominent, Micromelalopha troglodyta (Graeser) (Lepidoptera: Notodontidae), is an important pest of poplar in China. Glutathione S-transferases are known to be responsible for adaptation mechanisms of M. troglodyta. Thus, the tissue distribution and kinetic constants of glutathione S-transferase activity in the small prominent were studied. Significant differences in glutathione S-transferase (GST) activity and distribution percentages of GST activity and kinetic characteristics were observed among 4 tissues (head, midgut, fat body and integument). Furthermore, the inhibition of glutathione S-transferase activity in 4 tissues by 21 inhibitors was conducted. The results showed the inhibition of GST activity of different tissues by 21 inhibitors is different. For GST activity in heads, chlorpyrifos, profenofos, lambda-cyhalothrin, fipronil and quercetin were the best inhibitors tested. Tannic acid was the most potent inhibitor of midgut GST activity. In the fat body, GST activity was inhibited most by tannic acid, chlorpyrifos and profenofos. The inhibitory effect of profenofos and phoxim was highest for GST activity in the integument. Our results showed that glutathione S-transferases in different tissues are qualitatively different in isozyme composition and thus different in sensitivity to inhibitors.
37
Meyer, D. J., e M. Thomas. "Characterization of rat spleen prostaglandin H d-isomerase as a sigma-class GSH transferase". Biochemical Journal 311, n. 3 (1 novembre 1995): 739–42. http://dx.doi.org/10.1042/bj3110739.
Testo completoAbstract (sommario):
The prostaglandin H D-isomerase of rat immune accessory cells has been purified from spleen by a simple procedure, and its high specificity and activity [Urade, Fujimoto, Ujihara and Hayaishi (1987) J. Biol. Chem. 262, 3820-3825] have been confirmed in an assay coupled to prostaglandin H synthase. The enzyme also decreases the formation of 12[S]-hydroxy-5,8,10-heptadecatrienoic acid formed by the synthase in the presence of GSH and increases the overall rate of arachidonate oxidation. A partial amino acid sequence shows a strong relationship to GSH transferases of parasitic helminths and molluscs, indicating that it is the first example of a vertebrate sigma-class GSH transferase, and suggesting that certain helminth GSH transferases may be involved in prostaglandin synthesis.
38
Cao, Min, Bryan A. Bernat, Zhepeng Wang, Richard N. Armstrong e John D. Helmann. "FosB, a Cysteine-Dependent Fosfomycin Resistance Protein under the Control of ςW, an Extracytoplasmic-Function ς Factor in Bacillus subtilis". Journal of Bacteriology 183, n. 7 (1 aprile 2001): 2380–83. http://dx.doi.org/10.1128/jb.183.7.2380-2383.2001.
Testo completoAbstract (sommario):
ABSTRACT We demonstrate that the Bacillus subtilis fosB(yndN)gene encodes a fosfomycin resistance protein. Expression offosB requires ςW, and both fosBand sigW mutants are fosfomycin sensitive. FosB is a metallothiol transferase related to the FosA class of Mn2+-dependent glutathione transferases but with a preference for Mg2+ and l-cysteine as cofactors.
39
Næssan, Cecilia L., Wolfgang Egge-Jacobsen, Ryan W. Heiniger, Matthew C. Wolfgang, Finn Erik Aas, Åsmund Røhr, Hanne C. Winther-Larsen e Michael Koomey. "Genetic and Functional Analyses of PptA, a Phospho-Form Transferase Targeting Type IV Pili in Neisseria gonorrhoeae". Journal of Bacteriology 190, n. 1 (19 ottobre 2007): 387–400. http://dx.doi.org/10.1128/jb.00765-07.
Testo completoAbstract (sommario):
ABSTRACT The PilE pilin subunit protein of Neisseria gonorrhoeae undergoes unique covalent modifications with phosphoethanolamine (PE) and phosphocholine (PC). The pilin phospho-form transferase A (PptA) protein, required for these modifications, shows sequence relatedness with and architectural similarities to lipopolysaccharide PE transferases. Here, we used regulated expression and mutagenesis as means to better define the relationships between PptA structure and function, as well as to probe the mechanisms by which other factors impact the system. We show here that pptA expression is coupled at the level of transcription to its distal gene, murF, in a division/cell wall gene operon and that PptA can act in a dose-dependent fashion in PilE phospho-form modification. Molecular modeling and site-directed mutagenesis provided the first direct evidence that PptA is a member of the alkaline phosphatase superfamily of metalloenzymes with similar metal-binding sites and conserved structural folds. Through phylogenetic analyses and sequence alignments, these conclusions were extended to include the lipopolysaccharide PE transferases, including members of the disparate Lpt6 subfamily, and the MdoB family of phosphoglycerol transferases. Each of these enzymes thus likely acts as a phospholipid head group transferase whose catalytic mechanism involves a trans-esterification step generating a protein-phospho-form ester intermediate. Coexpression of PptA with PilE in Pseudomonas aeruginosa resulted in high levels of PE modification but was not sufficient for PC modification. This and other findings show that PptA-associated PC modification is governed by as-yet-undefined ancillary factors unique to N. gonorrhoeae.
40
Tahir, M. K., C. Guthenberg e B. Mannervik. "Glutathione transferases in rat hepatoma cells. Effects of ascites cells on the isoenzyme pattern in liver and induction of glutathione transferases in the tumour cells". Biochemical Journal 257, n. 1 (1 gennaio 1989): 215–20. http://dx.doi.org/10.1042/bj2570215.
Testo completoAbstract (sommario):
Rat hepatoma cells grown intraperitoneally as an ascites tumour were analysed with respect to their contents of cytosolic glutathione transferases. In contrast with normal liver tissue, the hepatoma cells were dominated by the class Pi glutathione transferase 7-7. All the major hepatic enzyme forms were down-regulated to almost undetectable concentrations. Livers of rats bearing ascites-hepatoma cells expressed low, but significant, amounts of protein which, by electrophoretic and immunochemical properties, appeared identical with transferase 7-7. This enzyme is not detectable in normal hepatocytes. Treatment of rats with trans-stilbene oxide induced the expression of transferase 7-7 in the livers of normal rats as well as in hepatoma-cell-bearing animals. In addition, a 2-fold induction of transferase 7-7 was measured in the hepatoma ascites cells. No significant elevation of any other enzyme forms in the hepatoma cells was noted.
41
Shimoji, Miyuki, e Yoko Aniya. "Glutathione S-Transferases in Rat Testis Microsomes: Comparison with Liver Transferase". Journal of Biochemistry 115, n. 6 (giugno 1994): 1128–34. http://dx.doi.org/10.1093/oxfordjournals.jbchem.a124468.
Testo completo
42
Nigam, Rita, Tracy Whiting e Brian M. Bennett. "Effect of inhibitors of glutathione S-transferase on glyceryl trinitrate activity in isolated rat aorta". Canadian Journal of Physiology and Pharmacology 71, n. 2 (1 febbraio 1993): 179–84. http://dx.doi.org/10.1139/y93-025.
Testo completoAbstract (sommario):
We investigated the role of glutathione S-transferases (enzymes known to biotransform organic nitrates) in the vascular action of glyceryl trinitrate (GTN). Relaxation of phenylephrine-contracted rat aortic strips was assessed in the presence or absence of the glutathione S-transferase inhibitors Basilen Blue, bromosulfophthalein, Rose Bengal, hematin, chlorotriphenyltin, and (octyloxy)benzoylvinylglutathione. Whereas none of the inhibitors increased the EC50 for GTN relaxation, glutathione S-transferase activity in the 100 000 × g supernatant fraction of rat aorta was inhibited markedly by most of the inhibitors. In addition, GTN-stimulated activation of aortic guanylyl cyclase in broken-cell preparations was attenuated by all of the glutathione S-transferase inhibitors, suggesting a direct inhibitory action on guanylyl cyclase. In other experiments using aortic strips preexposed to phenylephrine, the inhibitors had no effect on GTN-induced cyclic GMP accumulation or on vascular biotransformation of GTN. In contrast, both Basilen Blue and bromosulfophthalein significantly inhibited GTN-induced relaxation of K+-contracted aortic strips, and Basilen Blue significantly inhibited GTN biotransformation in aortic strips preexposed to 25 mM K+. This may be due to a more favourable electrochemical gradient for entry of the inhibitors into membrane-depolarized tissues. We conclude that vascular glutathione S-transferases play a role in mediating the vasodilator actions of GTN in intact tissues in vitro, but that this appears to depend upon the nature of the contractile agent used in such studies.Key words: glyceryl trinitrate, glutathione S-transferase, cyclic GMP, vascular smooth muscle, biotransformation.
43
van Grinsven, Koen W. A., Silke Rosnowsky, Susanne W. H. van Weelden, Simone Pütz, Mark van der Giezen, William Martin, Jaap J. van Hellemond, Aloysius G. M. Tielens e Katrin Henze. "Acetate:Succinate CoA-transferase in the Hydrogenosomes of Trichomonas vaginalis". Journal of Biological Chemistry 283, n. 3 (16 novembre 2007): 1411–18. http://dx.doi.org/10.1074/jbc.m702528200.
Testo completoAbstract (sommario):
Acetate:succinate CoA-transferases (ASCT) are acetate-producing enzymes in hydrogenosomes, anaerobically functioning mitochondria and in the aerobically functioning mitochondria of trypanosomatids. Although acetate is produced in the hydrogenosomes of a number of anaerobic microbial eukaryotes such as Trichomonas vaginalis, no acetate producing enzyme has ever been identified in these organelles. Acetate production is the last unidentified enzymatic reaction of hydrogenosomal carbohydrate metabolism. We identified a gene encoding an enzyme for acetate production in the genome of the hydrogenosome-containing protozoan parasite T. vaginalis. This gene shows high similarity to Saccharomyces cerevisiae acetyl-CoA hydrolase and Clostridium kluyveri succinyl-CoA:CoA-transferase. Here we demonstrate that this protein is expressed and is present in the hydrogenosomes where it functions as the T. vaginalis acetate:succinate CoA-transferase (TvASCT). Heterologous expression of TvASCT in CHO cells resulted in the expression of an active ASCT. Furthermore, homologous overexpression of the TvASCT gene in T. vaginalis resulted in an equivalent increase in ASCT activity. It was shown that the CoA transferase activity is succinate-dependent. These results demonstrate that this acetyl-CoA hydrolase/transferase homolog functions as the hydrogenosomal ASCT of T. vaginalis. This is the first hydrogenosomal acetate-producing enzyme to be identified. Interestingly, TvASCT does not share any similarity with the mitochondrial ASCT from Trypanosoma brucei, the only other eukaryotic succinate-dependent acetyl-CoA-transferase identified so far. The trichomonad enzyme clearly belongs to a distinct class of acetate:succinate CoA-transferases. Apparently, two completely different enzymes for succinate-dependent acetate production have evolved independently in ATP-generating organelles.
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El-Sayed, S., J. Hemingway e R. P. Lane. "Susceptibility baselines for DDT metabolism and related enzyme systems in the sandfly Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae)". Bulletin of Entomological Research 79, n. 4 (novembre 1989): 679–84. http://dx.doi.org/10.1017/s0007485300018836.
Testo completoAbstract (sommario):
AbstractDDT metabolism in Phlebotomus papatasi (Scopoli) was investigated and compared to that in DDT-resistant and susceptible strains of Culex quinquefasciatus Say and Anopheles gambiae Giles with the objective of establishing baselines for sandfly studies. P. papatasi produced eight metabolites of DDT, with DDE predominating, as in the two mosquito species. Both oxidases and glutathione transferases were found to be involved in DDT metabolism in insecticide-susceptible adults of P. papatasi. The activity level of glutathione transferases and the reduced and oxidized difference spectra of cytochrome P-450 were measured spectrophotometrically. The level of glutathione transferase activity in P. papatasi was lower than that in susceptible C. quinquefasciatus adults when expressed in terms of the activity per milligram of soluble protein but, in contrast, the cytochrome P-450 was slightly higher in both the reduced and oxidized states.
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Hayes, J. D., e T. J. Mantle. "Use of immuno-blot techniques to discriminate between the glutathione S-transferase Yf, Yk, Ya, Yn/Yb and Yc subunits and to study their distribution in extrahepatic tissues. Evidence for three immunochemically distinct groups of transferase in the rat". Biochemical Journal 233, n. 3 (1 febbraio 1986): 779–88. http://dx.doi.org/10.1042/bj2330779.
Testo completoAbstract (sommario):
The glutathione S-transferases are dimeric enzymes whose subunits can be defined by their mobility during sodium dodecyl sulphate/polyacrylamide-gel electrophoresis as Yf (Mr 24,500), Yk (Mr 25,000), Ya (Mr 25,500), Yn (Mr 26,500), Yb1 (Mr 27,000), Yb2 (Mr 27,000) and Yc (Mr 28,500) [Hayes (1986) Biochem. J. 233, 789-798]. Antisera were raised against each of these subunits and their specificities assessed by immuno-blotting. The transferases in extrahepatic tissues were purified by using, sequentially, S-hexylglutathione and glutathione affinity chromatography. Immune-blotting was employed to identify individual transferase polypeptides in the enzyme pools from various organs. The immuno-blots showed marked tissue-specific expression of transferase subunits. In contrast with other subunits, the Yk subunit showed poor affinity for S-hexylglutathione-Sepharose 6B in all tissues examined, and subsequent use of glutathione and glutathione affinity chromatography. Immuno-blotting was employed to identify a new cytosolic polypeptide, or polypeptides, immunochemically related to the Yk subunit but with an electrophoretic mobility similar to that of the Yc subunit; high concentrations of the new polypeptide(s) are present in colon, an organ that lacks Yc.
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Cashman, Timothy J., e Chinmay M. Trivedi. "N-Acetyl Transferases". Circulation Research 128, n. 8 (16 aprile 2021): 1170–72. http://dx.doi.org/10.1161/circresaha.121.319049.
Testo completo
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Ketterman, Albert J., Chonticha Saisawang e Jantana Wongsantichon. "Insect glutathione transferases". Drug Metabolism Reviews 43, n. 2 (17 febbraio 2011): 253–65. http://dx.doi.org/10.3109/03602532.2011.552911.
Testo completo
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MANTLE, TIMOTHY J., FIONA M. McCUSKER, MICHAEL PHILLIPS e SINEAD BOYCE. "Glutathione S-transferases". Biochemical Society Transactions 18, n. 2 (1 aprile 1990): 175–77. http://dx.doi.org/10.1042/bst0180175.
Testo completo
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SUGUMARAN, Geetha, Maya KATSMAN e E. Jeremiah SILBERT. "Subcellular co-localization and potential interaction of glucuronosyltransferases with nascent proteochondroitin sulphate at Golgi sites of chondroitin synthesis". Biochemical Journal 329, n. 1 (1 gennaio 1998): 203–8. http://dx.doi.org/10.1042/bj3290203.
Testo completoAbstract (sommario):
Microsomal membranes from chick embryo epiphyseal cartilage were fractionated by equilibrium sucrose-density-gradient centrifugation and assayed for GlcA (glucuronic acid) transferase I (the enzyme that transfers GlcA from UDP-GlcA to Gal-Gal-Xyl of proteochondroitin linkage region), for comparison with GlcA transferase II (the GlcA transferase of chondroitin polymerization). Gal(β1-3)Galβ1-methyl (disaccharide) and GalNAc(β1-4)GlcA(β1-3)GalNAc(β1-4)GlcA(β1-3)GalNAc (pentasaccharide) were used respectively as acceptors of [14C]GlcA from UDP-[14C]GlcA. Distributions of the two GlcA transferase activities in the sucrose-density-gradient fractions were compared with each other and with the previously reported distribution of the activities of Gal transferases (UDP-Gal to ovalbumin, and to xylose of the proteochondroitin linkage region) and GalNAc (N-acetylgalactosamine) transferase II of chondroitin polymerization. The linkage-region GlcA transferase I had a dual Golgi distribution similar to that of chondroitin-polymerizing GlcA transferase II and distinctly different from the distribution of linkage-region Gal transferases I and II, which were found exclusively in the heavier fractions. Solubilized GlcA transferase I was partly purified by sequential use of Q-Sepharose, heparin-Sepharose and wheatgerm agglutinin-agarose and was accompanied at each step by some of the GlcA transferase II activity. Both GlcA transferase I and II bound to the Q-Sepharose as though they were highly anionic. However, treatment with chondroitin ABC lyase eliminated the binding while markedly decreasing enzyme stability. The enzyme activities could not be reconstituted by adding chondroitin or chondroitin pentasaccharide to the chondroitin ABC lyase-treated enzymes. Incubation of the partly purified enzymes with both UDP-GlcA and UDP-GalNAc resulted in a 40-fold greater incorporation than with just one sugar nucleotide, indicating the presence of bound, nascent proteochondroitin serving as the acceptor for chondroitin polymerization. These results, together with the membrane co-localization, indicate that GlcA transferase I and GlcA transferase II occur closely together with nascent proteochondroitin at the site of synthesis and that this complex with the nascent proteochondroitin stabilizes both enzymes during purification.
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Chee, Chin-Soon, Irene Kit-Ping Tan e Zazali Alias. "Characterization of Affinity-Purified Isoforms ofAcinetobacter calcoaceticusY1 Glutathione Transferases". Scientific World Journal 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/750317.
Testo completoAbstract (sommario):
Glutathione transferases (GST) were purified from locally isolated bacteria,Acinetobacter calcoaceticusY1, by glutathione-affinity chromatography and anion exchange, and their substrate specificities were investigated. SDS-polyacrylamide gel electrophoresis revealed that the purified GST resolved into a single band with a molecular weight (MW) of 23 kDa. 2-dimensional (2-D) gel electrophoresis showed the presence of two isoforms, GST1 (pI 4.5) and GST2 (pI 6.2) with identical MW. GST1 was reactive towards ethacrynic acid, hydrogen peroxide, 1-chloro-2,4-dinitrobenzene, andtrans,trans-hepta-2,4-dienalwhile GST2 was active towards all substrates except hydrogen peroxide. This demonstrated that GST1 possessed peroxidase activity which was absent in GST2. This study also showed that only GST2 was able to conjugate GSH to isoproturon, a herbicide. GST1 and GST2 were suggested to be similar to F0KLY9 (putative glutathione S-transferase) and F0KKB0 (glutathione S-transferase III) ofAcinetobacter calcoaceticusstrain PHEA-2, respectively.