Articoli di riviste: "Enzymes Synthesis"

1

Malá, Š., P. Karasová, M. Marková e B. Králová. "Oligosaccharide synthesis using a-glucosidases of different origin". Czech Journal of Food Sciences 19, No. 2 (7 febbraio 2013): 57–61. http://dx.doi.org/10.17221/6576-cjfs.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

a-Glucosidase from Aspergillus awamori and intestinal a-glucosidase (saccharase-isomaltase complex) exhibited high transglycosylation activity and were able to synthesize tri- and tetrasaccharides during maltose hydrolysis. Both tested enzymes were also able to transfer the glucose residue to all tested monosaccharide acceptors (D-mannose, D-xylose, L-sorbose and D-galactose). Their transfer activity towards respective acceptors varied and their acceptor preference also depended on the origin of the enzyme. Out of the acceptors tested, both enzymes exhibited high transfer activity in xylose.

2

Herman, Richard Ansah, Xuan Zhu, Ellen Ayepa, Shuai You e Jun Wang. "Advances in the One-Step Approach of Polymeric Materials Using Enzymatic Techniques". Polymers 15, n. 3 (30 gennaio 2023): 703. http://dx.doi.org/10.3390/polym15030703.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

The formulation in which biochemical enzymes are administered in polymer science plays a key role in retaining their catalytic activity. The one-step synthesis of polymers with highly sequence-controlled enzymes is a strategy employed to provide enzymes with higher catalytic activity and thermostability in material sustainability. Enzyme-catalyzed chain growth polymerization reactions using activated monomers, protein–polymer complexation techniques, covalent and non-covalent interaction, and electrostatic interactions can provide means to develop formulations that maintain the stability of the enzyme during complex material processes. Multifarious applications of catalytic enzymes are usually attributed to their efficiency, pH, and temperature, thus, progressing with a critical structure-controlled synthesis of polymer materials. Due to the obvious economics of manufacturing and environmental sustainability, the green synthesis of enzyme-catalyzed materials has attracted significant interest. Several enzymes from microorganisms and plants via enzyme-mediated material synthesis have provided a viable alternative for the appropriate synthesis of polymers, effectively utilizing the one-step approach. This review analyzes more and deeper strategies and material technologies widely used in multi-enzyme cascade platforms for engineering polymer materials, as well as their potential industrial applications, to provide an update on current trends and gaps in the one-step synthesis of materials using catalytic enzymes.

3

O'Keefe, S. J., W. M. Bennet, A. R. Zinsmeister e M. W. Haymond. "Pancreatic enzyme synthesis and turnover in human subjects". American Journal of Physiology-Gastrointestinal and Liver Physiology 266, n. 5 (1 maggio 1994): G816—G821. http://dx.doi.org/10.1152/ajpgi.1994.266.5.g816.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Animal studies have shown that pancreatic enzyme secretion is independent of enzyme synthesis. To investigate this relationship in humans, we have coinfused 14C-labeled leucine tracer with cholecystokinin octapeptide in nine healthy adults for 4 h and measured the rate of appearance of secreted and newly labeled enzymes in the duodenum. Enzyme secretion was well maintained throughout, but newly labeled enzymes only appeared in juice between 75 and 101 min (median time, 86 min), indicating that initial secretion was dependent on the release of zymogen stores and that the median production time for new enzymes was 86 min. Between 85 and 225 min there was a curvilinear increase in the enrichment of secreted enzymes with newly synthesized enzymes, suggesting a median turnover rate of zymogen stores of 29%/h (range 12-47%/h). In conclusion, our results suggest that in healthy humans, postprandial pancreatic enzyme secretion is maintained by the export of a large stored pool and is not rate limited by enzyme synthesis, since it takes approximately 86 min for newly synthesized enzymes to take part in the digestive process.

4

Juwon, Arotupin Daniel, e Ogunmolu Funso Emmanuel. "Experimental Investigations on the Effects of Carbon and Nitrogen Sources on Concomitant Amylase and Polygalacturonase Production by Trichoderma viride BITRS-1001 in Submerged Fermentation". Biotechnology Research International 2012 (15 luglio 2012): 1–8. http://dx.doi.org/10.1155/2012/904763.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

The paper investigates the effects of different commercial carbon and nitrogen sources on the concomitant synthesis of amylase and polygalacturonase enzymes with the aim of optimizing them for maximal enzyme production. The microorganism used in this work was the fungus Trichoderma viride BITRS-1001, which had been previously identified as a highly active producer of amylase and polygalacturonase enzymes. The results showed that the different commercial carbon and nitrogen substrate significantly affected the concomitant syntheses of amylase and polygalacturonase in culture media supplemented with the different commercial carbon and nitrogen substrates. The result obtained suggested that for optimal and concomitant synthesis of the enzymes by Trichoderma viride BITRS-1001 in submerged fermentation, minimal medium supplemented with maltose and casein were the carbon and nitrogen substrates of choice.

5

Hu, Chong, Yunxiu Bai, Miao Hou, Yisu Wang, Licheng Wang, Xun Cao, Chiu-Wing Chan et al. "Defect-induced activity enhancement of enzyme-encapsulated metal-organic frameworks revealed in microfluidic gradient mixing synthesis". Science Advances 6, n. 5 (gennaio 2020): eaax5785. http://dx.doi.org/10.1126/sciadv.aax5785.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Mimicking the cellular environment, metal-organic frameworks (MOFs) are promising for encapsulating enzymes for general applications in environments often unfavorable for native enzymes. Markedly different from previous researches based on bulk solution synthesis, here, we report the synthesis of enzyme-embedded MOFs in a microfluidic laminar flow. The continuously changed concentrations of MOF precursors in the gradient mixing on-chip resulted in structural defects in products. This defect-generating phenomenon enables multimodal pore size distribution in MOFs and therefore allows improved access of substrates to encapsulated enzymes while maintaining the protection to the enzymes. Thus, the as-produced enzyme-MOF composites showed much higher (~one order of magnitude) biological activity than those from conventional bulk solution synthesis. This work suggests that while microfluidic flow synthesis is currently underexplored, it is a promising strategy in producing highly active enzyme-MOF composites.

6

Bur, Daniel, Marcel A. Luyten, Hla Wynn, Louis R. Provencher, J. Bryan Jones, Marvin Gold, James D. Friesen, Anthony R. Clarke e J. John Holbrook. "An evaluation of the substrate specificity and asymmetric synthesis potential of the cloned L-lactate dehydrogenase from Bacillusstearothermophilus". Canadian Journal of Chemistry 67, n. 6 (1 giugno 1989): 1065–70. http://dx.doi.org/10.1139/v89-161.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

The potential utility of the L-lactate dehydrogenase of Bacillusstearothermophilus (BSLDH) for stereospecific, preparative-scale reductions of α-keto acids to (S)-α-hydroxy acids of > 99% ee has been demonstrated. BSLDH is a stable, thermophilic, enzyme whose gene has been cloned into a high-expression vector to assure its plentiful supply. Its specificity for keto acid substrates possessing straight- and branched-chain alkyl, cyclopropyl, or phenyl groups has been evaluated in preparative and kinetic terms, and compared with that of the mammalian pig heart enzyme (PHLDH). The specificities of BSLDH and PHLDH are similar, with branched alkyl-chain keto acids being poor substrates for both enzymes. Keywords: enzymes in organic syntheses, lactate dehydrogenase, asymmetric synthesis.

7

Smith, A. G. "Subcellular localization of two porphyrin-synthesis enzymes in Pisum sativum (pea) and Arum (cuckoo-pint) species". Biochemical Journal 249, n. 2 (15 gennaio 1988): 423–28. http://dx.doi.org/10.1042/bj2490423.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

The subcellular location of the two porphyrin-synthesis enzymes 5-aminolaevulinate dehydratase (ALAD) and porphobilinogen deaminase (PBGD) was investigated in Pisum sativum (pea) leaves and spadices of Arum (cuckoo-pint). Throughout the tissue-fractionation procedures the distribution of the two enzymes paralleled that of the plastid marker enzyme (ADP-glucose pyrophosphorylase), even in Arum, a tissue where the synthesis of non-plastid haem is predominant. The distribution of cytosolic marker enzyme (lactate dehydrogenase) was significantly different from that of ALAD and PBGD and, although purified mitochondria from both species had some residual activity, this was always less than contaminating plastid marker enzyme. The results suggest that ALAD and PBGD are exclusively plastid enzymes. The significance of this for the role of plastids in cellular porphyrin synthesis is discussed.

8

Hai guan Ding, Hai guan Ding, Zhi qiang Cai Zhi qiang Cai, Ling Hou Ling Hou, Zhi quan Hu Zhi quan Hu, Zheng sheng Jin Zheng sheng Jin, Di Xu Di Xu, Hui Cao Miao miao Meng Hui Cao Miao miao Meng, Yu Hui Xie Yu Hui Xie e De qiang Zheng De qiang Zheng. "Synthesis and Evaluation of Some Novel 6-Substituted Quinazoline Derivatives as Antitumor Agents". Journal of the chemical society of pakistan 41, n. 1 (2019): 186. http://dx.doi.org/10.52568/000716/jcsp/41.01.2019.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

A series of novel 6-substituted quinazoline derivatives were synthesised as epidermal growth factor receptor(EGFR) and Human epidermal growth factor receptor 2 (HER2)inhibitors in our lab. The novel compounds were measured for their dual enzyme inhibition as well as their cytotoxic activity on MCF7 cell line. The results revealed that all the compounds showed inhibition of both enzymes. Compound 5c showed the best inhibitory activity against both enzymes and IC50 of its was 2.6 nM against EGFR kinases and 4.3 nM against HER2 kinases, respectively. Most of the measured compounds showed to antitumor activity on MCF7.

9

Morrow, Cary J. "Biocatalytic Synthesis of Polyesters Using Enzymes". MRS Bulletin 17, n. 11 (novembre 1992): 43–47. http://dx.doi.org/10.1557/s0883769400046650.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Plants and animals have been exploited as sources of materials for centuries but, as our ability to analyze and fractionate them has progressed, the extraordinary range of properties available from materials produced by living systems has continued to grow. Doi, in another article in this issue of the MRS Bulletin, presents a discussion of a group of naturally occurring polyesters related to poly(beta-hydroxybutyrate). These polyesters are formed in vivo by several microorganisms as part of an energy storage scheme. Research on these systems has allowed growth conditions to be found that can lead, in a controlled fashion, to a number of copolymers. Useful materials based on these bacterial polyesters appear to be at hand.The in-vivo formation of polyesters in microorganisms also illustrates several of the important reasons for examining biocatalytic polymer synthesis. First, unlike most industrial syntheses of polyesters, the poly(beta-hydroxybutyrate) biosynthesis occurs at a near-ambient temperature using a carbohydrate feedstock. Second, and perhaps most importantly, the stored polyesters are readily biodegraded by the bacteria that manufacture them, so materials based on these polyesters should also be biodegradable. Third, although there are side chains along the polymer backbone, they are introduced in a highly stereo-specific fashion during in-vivo synthesis, leading to an entirely stereoregular polyester. However, along with these advantages, there are also significant limitations to bacterial polyester synthesis. First, there are some substrates that are not incorporated into the polyester by the bacteria. Second, normal metabolism leads to the polyester, always incorporating a fraction of hydroxybutyrate monomers. Third, the backbone is always comprised of four-atom, A-B type 3-hydroxy acid repeat units with variations appearing in the side chain at carbon-3.

10

Wong, Chi-Huey. "Enzymes for Glycoprotein Synthesis". CHIMIA International Journal for Chemistry 63, n. 6 (24 giugno 2009): 318–26. http://dx.doi.org/10.2533/chimia.2009.318.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

11

ORITANI, Takayuki. "Organic synthesis using enzymes." Journal of the agricultural chemical society of Japan 64, n. 2 (1990): 199–202. http://dx.doi.org/10.1271/nogeikagaku1924.64.199.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

12

Koeller, Kathryn M., e Chi-Huey Wong. "Enzymes for chemical synthesis". Nature 409, n. 6817 (gennaio 2001): 232–40. http://dx.doi.org/10.1038/35051706.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

13

Smith, Janet L. "Enzymes of nucleotide synthesis". Current Opinion in Structural Biology 5, n. 6 (dicembre 1995): 752–57. http://dx.doi.org/10.1016/0959-440x(95)80007-7.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

14

Scott, Nicola A., Laura J. Sharpe, Isabelle M. Capell-Hattam, Samuel J. Gullo, Winnie Luu e Andrew J. Brown. "The cholesterol synthesis enzyme lanosterol 14α-demethylase is post-translationally regulated by the E3 ubiquitin ligase MARCH6". Biochemical Journal 477, n. 2 (31 gennaio 2020): 541–55. http://dx.doi.org/10.1042/bcj20190647.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Cholesterol synthesis is a tightly controlled pathway, with over 20 enzymes involved. Each of these enzymes can be distinctly regulated, helping to fine-tune the production of cholesterol and its functional intermediates. Several enzymes are degraded in response to increased sterol levels, whilst others remain stable. We hypothesised that an enzyme at a key branch point in the pathway, lanosterol 14α-demethylase (LDM) may be post-translationally regulated. Here, we show that the preceding enzyme, lanosterol synthase is stable, whilst LDM is rapidly degraded. Surprisingly, this degradation is not triggered by sterols. However, the E3 ubiquitin ligase membrane-associated ring-CH-type finger 6 (MARCH6), known to control earlier rate-limiting steps in cholesterol synthesis, also control levels of LDM and the terminal cholesterol synthesis enzyme, 24-dehydrocholesterol reductase. Our work highlights MARCH6 as the first example of an E3 ubiquitin ligase that targets multiple steps in a biochemical pathway and indicates new facets in the control of cholesterol synthesis.

15

Abdi, Sayed Aliul Hasan, Abdulaziz Alzahrani, Saleh Alghamdi, Ali Alquraini e Adel Alghamdi. "Hexaconazole exposure ravages biosynthesis pathway of steroid hormones: revealed by molecular dynamics and interaction". Toxicology Research 11, n. 1 (16 dicembre 2021): 60–76. http://dx.doi.org/10.1093/toxres/tfab113.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Abstract Widespread application of hexaconazole for agriculture purpose poses a threat to human health by disrupting normal endocrine homeostasis. To avoid adverse health effects on human, it is crucial to identify the effects of hexaconazole on key enzymes responsible for steroidal hormone synthesis. In view of this, present study was conducted to investigate the interaction mechanisms of hexaconazole with key enzymes in comparison with their food drug administration (FDA) approved inhibitor by molecular docking and molecular dynamics simulations. Results indicate that hexaconazole contacts with the active site of the key enzymes required for steroidal hormonal synthesis. Results pertaining to root-mean-square deviation, root-mean-square calculation, radius of gyration, hydrogen bonding and solvent accessible surface area exhibited that the interaction pattern and stability of interaction of hexaconazole was similar to enzyme specific inhibitor. In addition, ligand and enzyme complex interaction energy of hexaconazole was almost similar to key enzyme and FDA-approved enzyme specific inhibitor complex. This study offers a molecular level of understanding of hexaconazole with different enzymes required for steroidal hormonal synthesis. Findings of the study clearly suggest that hexaconazole has efficacy to stably interact with various enzyme required to progress the pathway of hormonal synthesis. If incessant exposure of hexaconazole occurs during agricultural work it may lead to ravage hormonal synthesis or potent endocrine disruption. The result of binding energy and complex interaction energy is depicted in the graphical abstract.

16

Wild, D., R. von Schulthess e W. Gujer. "Synthesis of denitrification enzymes in activated sludge: modelling with structured biomass". Water Science and Technology 30, n. 6 (1 settembre 1994): 113–22. http://dx.doi.org/10.2166/wst.1994.0258.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Three mechanisms are responsible for microbiological elimination processes in activated sludge: the survival of qualified organisms in the ecological selection process, the expression of specific enzymes and the absence of inhibitors limiting enzyme activity. A mathematical model with structured biomass has been formulated to improve the description of data from denitrification experiments. The model includes synthesis and decay of denitrification enzymes and is able to predict nitrate, nitrite and N2O concentrations. Kinetic parameters have been estimated and used to simulate the effect of cell saturation with enzymes in a waste water treatment process. Low dissolved oxygen concentrations in the anoxic reactor reduce the denitrification efficiency equally by inhibiting enzyme activity and enzyme synthesis: at 0.5 gm−3 O2 enzyme decay causes a cell saturation of below 40 %. Enzyme synthesis can take place in the sludge blanket of a secondary sedimentation tank and improve denitrification efficiency. The benefit of modelling with structured biomass is shown. The comprehension of experimental observations has been improved, and plant design and operation can be optimized. However, the multitude of unknown parameters still may restrict the validity of complex models.

17

Junior, Ivaldo I., Emanuela Calcio Gaudino, Katia Martina, Giancarlo Cravotto, Rafael Luque e Rodrigo O. M. A. de Souza. "Improving the esterification activity of Pseudomonas fluorescens and Burkholderia cepacia lipases via cross-linked cyclodextrin immobilization". RSC Adv. 4, n. 86 (2014): 45772–77. http://dx.doi.org/10.1039/c4ra03797a.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Improving activities: solid cross-linked β-cyclodextrin enzymes can remarkably improve thermal stability and enzyme activity as compared to commercial immobilized enzymes in esterification reactions (e.g., monostearin synthesis).

18

Li, Can, Zhishang Shi, Jinxing Cai, Ping Wang, Fang Wang, Meiting Ju, Jinpeng Liu e Qilin Yu. "Synthesis of Phenylboronic Acid-Functionalized Magnetic Nanoparticles for Sensitive Soil Enzyme Assays". Molecules 27, n. 20 (14 ottobre 2022): 6883. http://dx.doi.org/10.3390/molecules27206883.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Soil enzymes, such as invertase, urease, acidic phosphatase and catalase, play critical roles in soil biochemical reactions and are involved in soil fertility. However, it remains a great challenge to efficiently concentrate soil enzymes and sensitively assess enzyme activity. In this study, we synthesized phenylboronic acid-functionalized magnetic nanoparticles to rapidly capture soil enzymes for sensitive soil enzyme assays. The iron oxide magnetic nanoparticles (MNPs) were firstly prepared by the co-precipitation method and then functionalized by (3-aminopropyl)triethoxysilane, polyethyleneimine and phenylboric acid in turn, obtaining the final nanoparticles (MNPPBA). Protein-capturing assays showed that the functionalized MNPs had a much higher protein-capturing capacity than the naked MNPs (56% versus 6%). Moreover, MNPPBA almost thoroughly captured the tested enzymes, i.e., urease, invertase, and alkaline phosphatase, from enzyme solutions. Based on MNPPBA, a soil enzyme assay method was developed by integration of enzyme capture, magnetic separation and trace enzyme analysis. The method was successfully applied in determining trace enzyme activity in rhizosphere soil. This study provides a strategy to sensitively determine soil enzyme activity for mechanistic investigation of soil fertility and plant–microbiome interaction.

19

Busch, Hagedoorn e Hanefeld. "Rhodococcus as A Versatile Biocatalyst in Organic Synthesis". International Journal of Molecular Sciences 20, n. 19 (26 settembre 2019): 4787. http://dx.doi.org/10.3390/ijms20194787.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

The application of purified enzymes as well as whole-cell biocatalysts in synthetic organic chemistry is becoming more and more popular, and both academia and industry are keen on finding and developing novel enzymes capable of performing otherwise impossible or challenging reactions. The diverse genus Rhodococcus offers a multitude of promising enzymes, which therefore makes it one of the key bacterial hosts in many areas of research. This review focused on the broad utilization potential of the genus Rhodococcus in organic chemistry, thereby particularly highlighting the specific enzyme classes exploited and the reactions they catalyze. Additionally, close attention was paid to the substrate scope that each enzyme class covers. Overall, a comprehensive overview of the applicability of the genus Rhodococcus is provided, which puts this versatile microorganism in the spotlight of further research.

20

Greicius, Aurimas, Tautvydas Baliutavicius, Egle Lastauskiene e Renata Gudiukaite. "Application of Milk Permeate as an Inducer for the Production of Microbial Recombinant Lipolytic Enzymes". Fermentation 9, n. 1 (28 dicembre 2022): 27. http://dx.doi.org/10.3390/fermentation9010027.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Recombinantly produced enzymes are applied in many fields, ranging from medicine to food and nutrition, production of detergents, textile, leather, paper, pulp, and plastics. Thus, the cost-effectiveness of recombinant enzyme synthesis is an important issue in biotechnological industry. Isopropyl-β-D-thiogalactoside (IPTG), an analog of lactose, is currently the most widely used chemical agent for the induction of recombinant enzyme synthesis. However, the use of IPTG can lead to production of toxic elements and can introduce physiological stress to cells. Thus, this study aims to find a simpler, cheaper, and safer way to produce recombinant enzymes. In this study, production of several previously designed recombinant lipolytic enzymes (GDEst-95 esterase, GD-95RM lipase, fused GDEst-lip lipolytic enzyme, and putative cutinase Cut+SP from Streptomyces scabiei 87.22) is induced in E. coli BL21 (DE3) using 4 mM milk permeate, a type of waste of the milk manufacturing process possessing >82% lactose. The SDS-PAGE analysis clearly indicates synthesis of all target enzymes during a 2–12 h post-induction timeframe. Further investigation of GDEst-95, GD-95RM, GDEst-lip, and Cut+SP biocatalysts was carried out spectrophotometrically and using zymography method, confirming production of fully active enzymes.

21

Sharpe, Laura J., Hudson W. Coates e Andrew J. Brown. "Post-translational control of the long and winding road to cholesterol". Journal of Biological Chemistry 295, n. 51 (13 ottobre 2020): 17549–59. http://dx.doi.org/10.1074/jbc.rev120.010723.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

The synthesis of cholesterol requires more than 20 enzymes, many of which are intricately regulated. Post-translational control of these enzymes provides a rapid means for modifying flux through the pathway. So far, several enzymes have been shown to be rapidly degraded through the ubiquitin–proteasome pathway in response to cholesterol and other sterol intermediates. Additionally, several enzymes have their activity altered through phosphorylation mechanisms. Most work has focused on the two rate-limiting enzymes: 3-hydroxy-3-methylglutaryl CoA reductase and squalene monooxygenase. Here, we review current literature in the area to define some common themes in the regulation of the entire cholesterol synthesis pathway. We highlight the rich variety of inputs controlling each enzyme, discuss the interplay that exists between regulatory mechanisms, and summarize findings that reveal an intricately coordinated network of regulation along the cholesterol synthesis pathway. We provide a roadmap for future research into the post-translational control of cholesterol synthesis, and no doubt the road ahead will reveal further twists and turns for this fascinating pathway crucial for human health and disease.

22

Biswas, Ansuman, e Mukund Thattai. "Promiscuity and specificity of eukaryotic glycosyltransferases". Biochemical Society Transactions 48, n. 3 (15 giugno 2020): 891–900. http://dx.doi.org/10.1042/bst20190651.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Glycosyltransferases are a large family of enzymes responsible for covalently linking sugar monosaccharides to a variety of organic substrates. These enzymes drive the synthesis of complex oligosaccharides known as glycans, which play key roles in inter-cellular interactions across all the kingdoms of life; they also catalyze sugar attachment during the synthesis of small-molecule metabolites such as plant flavonoids. A given glycosyltransferase enzyme is typically responsible for attaching a specific donor monosaccharide, via a specific glycosidic linkage, to a specific moiety on the acceptor substrate. However these enzymes are often promiscuous, able catalyze linkages between a variety of donors and acceptors. In this review we discuss distinct classes of glycosyltransferase promiscuity, each illustrated by enzymatic examples from small-molecule or glycan synthesis. We highlight the physical causes of promiscuity, and its biochemical consequences. Structural studies of glycosyltransferases involved in glycan synthesis show that they make specific contacts with ‘recognition motifs’ that are much smaller than the full oligosaccharide substrate. There is a wide range in the sizes of glycosyltransferase recognition motifs: highly promiscuous enzymes recognize monosaccharide or disaccharide motifs across multiple oligosaccharides, while highly specific enzymes recognize large, complex motifs found on few oligosaccharides. In eukaryotes, the localization of glycosyltransferases within compartments of the Golgi apparatus may play a role in mitigating the glycan variability caused by enzyme promiscuity.

23

Koga, Yosuke, e Hiroyuki Morii. "Biosynthesis of Ether-Type Polar Lipids in Archaea and Evolutionary Considerations". Microbiology and Molecular Biology Reviews 71, n. 1 (marzo 2007): 97–120. http://dx.doi.org/10.1128/mmbr.00033-06.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

SUMMARY This review deals with the in vitro biosynthesis of the characteristics of polar lipids in archaea along with preceding in vivo studies. Isoprenoid chains are synthesized through the classical mevalonate pathway, as in eucarya, with minor modifications in some archaeal species. Most enzymes involved in the pathway have been identified enzymatically and/or genomically. Three of the relevant enzymes are found in enzyme families different from the known enzymes. The order of reactions in the phospholipid synthesis pathway (glycerophosphate backbone formation, linking of glycerophosphate with two radyl chains, activation by CDP, and attachment of common polar head groups) is analogous to that of bacteria. sn-Glycerol-1-phosphate dehydrogenase is responsible for the formation of the sn-glycerol-1-phosphate backbone of phospholipids in all archaea. After the formation of two ether bonds, CDP-archaeol acts as a common precursor of various archaeal phospholipid syntheses. Various phospholipid-synthesizing enzymes from archaea and bacteria belong to the same large CDP-alcohol phosphatidyltransferase family. In short, the first halves of the phospholipid synthesis pathways play a role in synthesis of the characteristic structures of archaeal and bacterial phospholipids, respectively. In the second halves of the pathways, the polar head group-attaching reactions and enzymes are homologous in both domains. These are regarded as revealing the hybrid nature of phospholipid biosynthesis. Precells proposed by Wächtershäuser are differentiated into archaea and bacteria by spontaneous segregation of enantiomeric phospholipid membranes (with sn-glycerol-1-phosphate and sn-glycerol-3-phosphate backbones) and the fusion and fission of precells. Considering the nature of the phospholipid synthesis pathways, we here propose that common phospholipid polar head groups were present in precells before the differentiation into archaea and bacteria.

24

Rolf, Jascha, Katrin Rosenthal e Stephan Lütz. "Application of Cell-Free Protein Synthesis for Faster Biocatalyst Development". Catalysts 9, n. 2 (19 febbraio 2019): 190. http://dx.doi.org/10.3390/catal9020190.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Cell-free protein synthesis (CFPS) has become an established tool for rapid protein synthesis in order to accelerate the discovery of new enzymes and the development of proteins with improved characteristics. Over the past years, progress in CFPS system preparation has been made towards simplification, and many applications have been developed with regard to tailor-made solutions for specific purposes. In this review, various preparation methods of CFPS systems are compared and the significance of individual supplements is assessed. The recent applications of CFPS are summarized and the potential for biocatalyst development discussed. One of the central features is the high-throughput synthesis of protein variants, which enables sophisticated approaches for rapid prototyping of enzymes. These applications demonstrate the contribution of CFPS to enhance enzyme functionalities and the complementation to in vivo protein synthesis. However, there are different issues to be addressed, such as the low predictability of CFPS performance and transferability to in vivo protein synthesis. Nevertheless, the usage of CFPS for high-throughput enzyme screening has been proven to be an efficient method to discover novel biocatalysts and improved enzyme variants.

25

Mu, Ruipu, Zhaoshuai Wang, Max C. Wamsley, Colbee N. Duke, Payton H. Lii, Sarah E. Epley, London C. Todd e Patty J. Roberts. "Application of Enzymes in Regioselective and Stereoselective Organic Reactions". Catalysts 10, n. 8 (24 luglio 2020): 832. http://dx.doi.org/10.3390/catal10080832.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Nowadays, biocatalysts have received much more attention in chemistry regarding their potential to enable high efficiency, high yield, and eco-friendly processes for a myriad of applications. Nature’s vast repository of catalysts has inspired synthetic chemists. Furthermore, the revolutionary technologies in bioengineering have provided the fast discovery and evolution of enzymes that empower chemical synthesis. This article attempts to deliver a comprehensive overview of the last two decades of investigation into enzymatic reactions and highlights the effective performance progress of bio-enzymes exploited in organic synthesis. Based on the types of enzymatic reactions and enzyme commission (E.C.) numbers, the enzymes discussed in the article are classified into oxidoreductases, transferases, hydrolases, and lyases. These applications should provide us with some insight into enzyme design strategies and molecular mechanisms.

26

Fateev, Ilja V., Maria A. Kostromina, Yuliya A. Abramchik, Barbara Z. Eletskaya, Olga O. Mikheeva, Dmitry D. Lukoshin, Evgeniy A. Zayats et al. "Multi-Enzymatic Cascades in the Synthesis of Modified Nucleosides: Comparison of the Thermophilic and Mesophilic Pathways". Biomolecules 11, n. 4 (16 aprile 2021): 586. http://dx.doi.org/10.3390/biom11040586.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

A comparative study of the possibilities of using ribokinase → phosphopentomutase → nucleoside phosphorylase cascades in the synthesis of modified nucleosides was carried out. Recombinant phosphopentomutase from Thermus thermophilus HB27 was obtained for the first time: a strain producing a soluble form of the enzyme was created, and a method for its isolation and chromatographic purification was developed. It was shown that cascade syntheses of modified nucleosides can be carried out both by the mesophilic and thermophilic routes from D-pentoses: ribose, 2-deoxyribose, arabinose, xylose, and 2-deoxy-2-fluoroarabinose. The efficiency of 2-chloradenine nucleoside synthesis decreases in the following order: Rib (92), dRib (74), Ara (66), F-Ara (8), and Xyl (2%) in 30 min for mesophilic enzymes. For thermophilic enzymes: Rib (76), dRib (62), Ara (32), F-Ara (<1), and Xyl (2%) in 30 min. Upon incubation of the reaction mixtures for a day, the amounts of 2-chloroadenine riboside (thermophilic cascade), 2-deoxyribosides (both cascades), and arabinoside (mesophilic cascade) decreased roughly by half. The conversion of the base to 2-fluoroarabinosides and xylosides continued to increase in both cases and reached 20-40%. Four nucleosides were quantitatively produced by a cascade of enzymes from D-ribose and D-arabinose. The ribosides of 8-azaguanine (thermophilic cascade) and allopurinol (mesophilic cascade) were synthesized. For the first time, D-arabinosides of 2-chloro-6-methoxypurine and 2-fluoro-6-methoxypurine were synthesized using the mesophilic cascade. Despite the relatively small difference in temperatures when performing the cascade reactions (50 and 80 °C), the rate of product formation in the reactions with Escherichia coli enzymes was significantly higher. E. coli enzymes also provided a higher content of the target products in the reaction mixture. Therefore, they are more appropriate for use in the polyenzymatic synthesis of modified nucleosides.

27

Shi, Yuguang, e Dong Cheng. "Beyond triglyceride synthesis: the dynamic functional roles of MGAT and DGAT enzymes in energy metabolism". American Journal of Physiology-Endocrinology and Metabolism 297, n. 1 (luglio 2009): E10—E18. http://dx.doi.org/10.1152/ajpendo.90949.2008.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Monoacyglycerol acyltransferases (MGATs) and diacylglycerol acyltransferases (DGATs) catalyze two consecutive steps of enzyme reactions in the synthesis of triacylglycerols (TAGs). The metabolic complexity of TAG synthesis is reflected by the presence of multiple isoforms of MGAT and DGAT enzymes that differ in catalytic properties, subcellular localization, tissue distribution, and physiological functions. MGAT and DGAT enzymes play fundamental roles in the metabolism of monoacylglycerol (MAG), diacylglycerol (DAG), and triacylglycerol (TAG) that are involved in many aspects of physiological functions, such as intestinal fat absorption, lipoprotein assembly, adipose tissue formation, signal transduction, satiety, and lactation. The recent progress in the phenotypic characterization of mice deficient in MGAT and DGAT enzymes and the development of chemical inhibitors have revealed important roles of these enzymes in the regulation of energy homeostasis and insulin sensitivity. Consequently, selective inhibition of MGAT or DGAT enzymes by synthetic compounds may provide novel treatment for obesity and its related metabolic complications.

28

Fang, Jim-Min, Chun-Hung Lin, Curt W. Bradshaw e Chi-Huey Wong. "Enzymes in organic synthesis: oxidoreductions". Journal of the Chemical Society, Perkin Transactions 1, n. 8 (1995): 967. http://dx.doi.org/10.1039/p19950000967.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

29

Collier, Steve. "Asymmetric Organic Synthesis with Enzymes". Synthesis 2009, n. 15 (27 luglio 2009): 2650. http://dx.doi.org/10.1055/s-0029-1216915.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

30

Rosei, M. A., L. Mosca, C. Foppoli, R. Coccia e C. De Marco. "Alternative enzymes in melanin synthesis". Melanoma Research 5 (settembre 1995): 19. http://dx.doi.org/10.1097/00008390-199509001-00024.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

31

Hudlicky, Tomas. "Introduction to Enzymes in Synthesis". Chemical Reviews 111, n. 7 (13 luglio 2011): 3995–97. http://dx.doi.org/10.1021/cr200185s.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

32

BORMAN, STU. "Glycopeptide synthesis uses engineered enzymes". Chemical & Engineering News 71, n. 31 (2 agosto 1993): 25–28. http://dx.doi.org/10.1021/cen-v071n031.p025.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

33

Basavaiah, Deevi, e P. Rama Krishna. "Enantioselective synthesis using crude enzymes". Pure and Applied Chemistry 64, n. 8 (1 gennaio 1992): 1067–72. http://dx.doi.org/10.1351/pac199264081067.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

34

Bhupathy, M., D. L. Hughes, J. S. Amato, J. J. Bergan, J. L. Leazer, T. C. Lovelace, J. M. McNamara et al. "Enzymes and practical asymmetric synthesis". Pure and Applied Chemistry 64, n. 12 (1 gennaio 1992): 1939–44. http://dx.doi.org/10.1351/pac199264121939.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

35

Kent, Stephen. "Total chemical synthesis of enzymes". Journal of Peptide Science 9, n. 9 (2003): 574–93. http://dx.doi.org/10.1002/psc.475.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

36

Winkler, Margit, Martina Geier, Steven P. Hanlon, Bernd Nidetzky e Anton Glieder. "Human Enzymes for Organic Synthesis". Angewandte Chemie International Edition 57, n. 41 (11 settembre 2018): 13406–23. http://dx.doi.org/10.1002/anie.201800678.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

37

Turner, Nicholas J. "The Application of Enzymes in the Synthesis of Amino Acids, Peptides and Carbohydrates". Current Organic Chemistry 1, n. 1 (maggio 1997): 21–36. http://dx.doi.org/10.2174/1385272801666220121183432.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Enzymatic transformations have recently assumed great importance in the synthesis of enantiomerically pure amino acids and carbohydrates, particularly as the requirement for efficient methods in catalytic asymmetric synthesis increases. A large number of enzymes, that catalyse a wide range of different synthetic transformations, have been identified and are J currently being applied in many laboratories including our own. This Chapter will focus on recent work from the Edinburgh group and will address the application of those enzymes that catalyse the (i) hydrolysis of esters (ii) the ring-opening of oxazolones in. organic solvents (iii) the hydrolysis and synthesis of glycosides (iv) the asymmetric synthesis of carbon-carbon bonds. Emphasis will be placed on the development of protocols for carrying out these biocatalytic transformations on a medium to large scale. The use of .enzymes in the preparation of amino acid and carbohydrate derivatives will be illustrated by the syntheses of biologically active pharmaceutical intermediates and selected target molecules such as morphine-6-glucuronide, L-tert-leucine, pseudopeptides, and novel glycosidase inhibitors. Finally, a brief section on the use of enzymes in solid -phase synthesis will be included in which it will be shown that enzymes can be used not only to carry out selective transformations on a solid support, but also to act as highly selective reagents for the cleavage of the products by the design of appropriate enzymecleavable linker systems.

38

Medlock, Amy E., e Harry A. Dailey. "New Avenues of Heme Synthesis Regulation". International Journal of Molecular Sciences 23, n. 13 (5 luglio 2022): 7467. http://dx.doi.org/10.3390/ijms23137467.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

During erythropoiesis, there is an enormous demand for the synthesis of the essential cofactor of hemoglobin, heme. Heme is synthesized de novo via an eight enzyme-catalyzed pathway within each developing erythroid cell. A large body of data exists to explain the transcriptional regulation of the heme biosynthesis enzymes, but until recently much less was known about alternate forms of regulation that would allow the massive production of heme without depleting cellular metabolites. Herein, we review new studies focused on the regulation of heme synthesis via carbon flux for porphyrin synthesis to post-translations modifications (PTMs) that regulate individual enzymes. These PTMs include cofactor regulation, phosphorylation, succinylation, and glutathionylation. Additionally discussed is the role of the immunometabolite itaconate and its connection to heme synthesis and the anemia of chronic disease. These recent studies provide new avenues to regulate heme synthesis for the treatment of diseases including anemias and porphyrias.

39

Kohen, Amnon, Priyanka Singh e Qi Guo. "Chemoenzymatic Synthesis of Ubiquitous Biological Redox Cofactors". Synlett 28, n. 10 (10 aprile 2017): 1151–59. http://dx.doi.org/10.1055/s-0036-1588768.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Redox cofactors are utilized by a myriad of proteins, ranging from metabolic enzymes to those performing post-translational modifications. Labeled redox cofactors have served as a vital tool for a broad range of studies. This account describes chemoenzymatic syntheses of the isotopically labeled, biologically important redox cofactors: nicotinamide adenine dinucleotide, methylene tetrahydrofolate, and flavin nucleotides. An overview of the general strategy is presented. These examples demonstrate the utility of enzymatic synthesis.1 Introduction2 Nicotinamide Cofactors2.1 Synthesis of Remote-Labeled 14C-NADPH2.1.1 Synthesis of [Ad-14C]NADPH2.1.2 Synthesis of [Carbonyl-14C]NADPH2.2 Synthesis of S- and R-[4-3H]NADPH2.2.1 One-Step S- and Three-Step R-[4-3H]NADPH Synthesis2.2.2 One-Pot, One-Step R-[4-3H]NADPH Synthesis2.3 Synthesis of S- and R-[Ad-14C, 4-2H]NADPH2.3.1 One-Step S-, Three-Step R-[Ad-14C, 4-2H]NADPH Synthesis2.3.2 One-Pot, One-Step R-[Ad-14C, 4-2H]NADPH Synthesis3 Methylene Tetrahydrofolate4 Flavin Nucleotides5 Conclusions and Outlook

40

Anboo, Shamini, Sie Yon Lau, Jibrail Kansedo, Pow-Seng Yap, Tony Hadibarata e Azlina Harun Kamaruddin. "Synthesis of Enzyme-based Organic-Inorganic Hybrid Nanoflower Particles". MATEC Web of Conferences 377 (2023): 01011. http://dx.doi.org/10.1051/matecconf/202337701011.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Enzyme-incorporated hybrid nanostructures are the immobilization of enzymes and inorganic components that exhibits promising characteristics in various industries. The immobilization of enzymes onto nanomaterial is naturally based to accommodate the enzymatic activity, stability, recyclability as well as their catalytic functions. The designing of these conjugates can improve the overall enzymatic performance by imparting their novel properties onto the system in comparison to conventional free enzymes which experience drawbacks in terms of deactivation or denaturing. A facile and ultrafast method is described in this paper to synthesize a novel enzyme-incorporated lipase/Cu3(PO4)2 hybrid nanoflower (NF). The physical properties of the hybrid NF allow easier retrieval which indicates its higher reusability and recyclability value. The enzyme loading capacity was found to be 95.1% whereas, the catalytic performance of lipase/Cu3(PO4)2 hybrid NF at the optimal conditions resulted in a specific enzyme activity of 1752 U/g corresponding to an increment of 90.5% to that of free lipase. This indicates that the well-designed lipase/Cu3(PO4)2 hybrid NF to be highly efficient in industrial biocatalytic applications. Meanwhile, in future work, we aim to study its operational stability and reusability to enzymatically degrade biopolymers through hydrolysis process.

41

Díaz-Juárez, Julieta A., e Rolando Hernández-Muñoz. "Rat Liver Enzyme Release Depends on Blood Flow-Bearing Physical Forces Acting in Endothelium Glycocalyx rather than on Liver Damage". Oxidative Medicine and Cellular Longevity 2017 (2017): 1–15. http://dx.doi.org/10.1155/2017/1360565.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

We have found selective elevation of serum enzyme activities in rats subjected to partial hepatectomy (PH), apparently controlled by hemodynamic flow-bearing physical forces. Here, we assess the involvement of stretch-sensitive calcium channels and calcium mobilization in isolated livers, after chemical modifications of the endothelial glycocalyx and changing perfusion directionality. Inhibiting in vivo protein synthesis, we found that liver enzyme release is influenced by de novo synthesis of endothelial glycocalyx components, and released enzymes are confined into a liver “pool.” Moreover, liver enzyme release depended on extracellular calcium entry possibly mediated by stretch-sensitive calcium channels, and this endothelial-mediated mechanotransduction in liver enzyme release was also evidenced by modifying the glycocalyx carbohydrate components, directionality of perfusing flow rate, and the participation of nitric oxide (NO) and malondialdehyde (MDA), leading to modifications in the intracellular distribution of these enzymes mainly as nuclear enrichment of “mitochondrial” enzymes. In conclusion, the flow-induced shear stress may provide fine-tuned control of released hepatic enzymes through mediation by the endothelium glycocalyx, which provides evidence of a biological role of the enzyme release rather to be merely a biomarker for evaluating hepatotoxicity and liver damage, actually positively influencing progression of liver regeneration in mammals.

42

Kinner, Alina, Philipp Nerke, Regine Siedentop, Till Steinmetz, Thomas Classen, Katrin Rosenthal, Markus Nett, Jörg Pietruszka e Stephan Lütz. "Recent Advances in Biocatalysis for Drug Synthesis". Biomedicines 10, n. 5 (21 aprile 2022): 964. http://dx.doi.org/10.3390/biomedicines10050964.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Biocatalysis is constantly providing novel options for the synthesis of active pharmaceutical ingredients (APIs). In addition to drug development and manufacturing, biocatalysis also plays a role in drug discovery and can support many active ingredient syntheses at an early stage to build up entire scaffolds in a targeted and preparative manner. Recent progress in recruiting new enzymes by genome mining and screening or adapting their substrate, as well as product scope, by protein engineering has made biocatalysts a competitive tool applied in academic and industrial spheres. This is especially true for the advances in the field of nonribosomal peptide synthesis and enzyme cascades that are expanding the capabilities for the discovery and synthesis of new bioactive compounds via biotransformation. Here we highlight some of the most recent developments to add to the portfolio of biocatalysis with special relevance for the synthesis and late-stage functionalization of APIs, in order to bypass pure chemical processes.

43

Sood, Ankur, Seong Min Ji, Anuj Kumar e Sung Soo Han. "Enzyme-Triggered Crosslinked Hybrid Hydrogels for Bone Tissue Engineering". Materials 15, n. 18 (14 settembre 2022): 6383. http://dx.doi.org/10.3390/ma15186383.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

The quest to develop state-of-the-art hydrogels for bone tissue engineering has accompanied substantial innovation and significant progression in the field of bioactive hydrogels. Still, there is scope for advancement in this cell-friendly and biocompatible scaffold system. The crosslinking approaches used for hydrogel synthesis plays a decisive role in guiding and regulating the mechanical stability, network framework, macroscopic architect, immunological behaviors, and cellular responses. Until recently, enzyme-based crosslinking strategies were considered as the pinnacle in designing efficient hybrid hydrogel systems. A variety of enzymes have been explored for manufacturing hydrogels while taking the advantage of the biocompatible nature, specificity, ability to produce nontoxic by products and high efficiency of enzymes. The current review focuses on the utility of different enzymes as crosslinking agents for hydrogel formation with their application in bone tissue engineering. The field of enzyme crosslinked hydrogel synthesis is rapidly maturing with a lot of opportunities to be explored in bone tissue engineering. Enzyme-based in situ and externally crosslinked hydrogels for bone regeneration is an attractive field, and with innovation in using engineered enzymes this field will continue to flourish with clinical orientation.

44

Girard, M. T., M. Matsubara, C. Kublin, M. J. Tessier, C. Cintron e M. E. Fini. "Stromal fibroblasts synthesize collagenase and stromelysin during long-term tissue remodeling". Journal of Cell Science 104, n. 4 (1 aprile 1993): 1001–11. http://dx.doi.org/10.1242/jcs.104.4.1001.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

The process of connective tissue remodeling is an important mechanism contributing to tissue morphogenesis in development and homeostasis. Although it has long been known that remodeling tissues actively mediate collagenolysis, little is understood about the molecular mechanisms controlling this cell-regulated process. In this study, we examined the biosynthesis of collagenase and the related metalloproteinase, stromelysin, during remodeling of repair tissue deposited after mechanical injury to the rabbit cornea. Neither enzyme was synthesized by uninjured corneas; however, synthesis and secretion was detectable within one day after injury. Collagenase accumulated in its latent form while stromelysin appeared to be partially activated. Enzymes were synthesized by cells having a fibroblast phenotype. These cells were found within the stroma. New synthesis was correlated with accumulation of enzyme-specific mRNA. Highest levels of enzyme synthesis were observed in the repair tissue. However, stromal cells outside of the repairing area also synthesized both enzymes. The level of synthesis decreased in a gradient radiating from the repair tissue. Total synthetic levels in a given area of cornea were dependent on both the number of cells expressing enzyme and the rate of enzyme synthesis. Synthesis of collagenase was detected in repair tissue as long as nine months after injury. Our findings provide direct support for the hypothesis that new collagenase synthesis by cells in repair tissue is the first step in collagen degradation during long-term tissue remodeling.

45

CHASSAGNOLE, Christophe, David A. FELL, Badr RAÏS, Bernard KUDLA e Jean-Pierre MAZAT. "Control of the threonine-synthesis pathway in Escherichia coli: a theoretical and experimental approach". Biochemical Journal 356, n. 2 (24 maggio 2001): 433–44. http://dx.doi.org/10.1042/bj3560433.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

A computer simulation of the threonine-synthesis pathway in Escherichia coli Tir-8 has been developed based on our previous measurements of the kinetics of the pathway enzymes under near-physiological conditions. The model successfully simulates the main features of the time courses of threonine synthesis previously observed in a cell-free extract without alteration of the experimentally determined parameters, although improved quantitative fits can be obtained with small parameter adjustments. At the concentrations of enzymes, precursors and products present in cells, the model predicts a threonine-synthesis flux close to that required to support cell growth. Furthermore, the first two enzymes operate close to equilibrium, providing an example of a near-equilibrium feedback-inhibited enzyme. The predicted flux control coefficients of the pathway enzymes under physiological conditions show that the control of flux is shared between the first three enzymes: aspartate kinase, aspartate semialdehyde dehydrogenase and homoserine dehydrogenase, with no single activity dominating the control. The response of the model to the external metabolites shows that the sharing of control between the three enzymes holds across a wide range of conditions, but that the pathway flux is sensitive to the aspartate concentration. When the model was embedded in a larger model to simulate the variable demands for threonine at different growth rates, it showed the accumulation of free threonine that is typical of the Tir-8 strain at low growth rates. At low growth rates, the control of threonine flux remains largely with the pathway enzymes. As an example of the predictive power of the model, we studied the consequences of over-expressing different enzymes in the pathway.

46

Beardsley, S., S. Kunjara e A. L. Greenbaum. "Enzymes of the pathway of purine synthesis in the rat mammary gland. Changes in the lactation cycle and the effects of diabetes". Biochemical Journal 250, n. 2 (1 marzo 1988): 395–99. http://dx.doi.org/10.1042/bj2500395.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Measurements were made of the activities of the enzymes of the ‘de novo’ and salvage pathways of purine synthesis [phosphoribosyl pyrophosphate amidotransferase (EC 2.4.2.14), adenine phosphoribosyltransferase (EC 2.4.2.7) and hypoxanthine phosphoribosyltranferase (EC 2.4.2.8)] at different stages of the lactation cycle, and the effects of diabetes on the activity of these enzymes in lactation were studied. A distinctive pattern of enzyme change was observed, in which the ‘de novo’ pathway enzyme phosphoribosyl pyrophosphate amidotransferase increased sharply between days 10 and 14 of pregnancy, and then remained sensibly constant until the height of lactation, whereas the enzymes of the salvage pathway increased later in pregnancy and continued to rise during lactation. Diabetes severely depressed the activity of the enzymes of the salvage pathway, but appeared to be without effect on the ‘de novo’ pathway enzyme. These results are discussed in relation to the provision of purine precursors from tissues outside the mammary gland.

47

DAI, Z., Y. YIN e Z. WANG. "Activities of key enzymes involved in starch synthesis in grains of wheat under different irrigation patterns". Journal of Agricultural Science 147, n. 4 (22 aprile 2009): 437–44. http://dx.doi.org/10.1017/s0021859609008612.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

SUMMARYIt is generally accepted that sucrose phosphate synthase (SPS), sucrose synthase (SuSy), ADP-glucose pyrophosphorylase (AGPase), soluble starch synthase (SSS), granule-bound starch synthase (GBSS) and starch branching enzyme (SBE) play a key role in starch synthesis in wheat grains. Starch synthesis in wheat grains is influenced by genotype and environment. However, what is not known is the degree of variation in enzyme activities during starch accumulation of wheat cultivars field-grown in different water regimes. The present study was undertaken to determine whether irrigation patterns could cause differences in starch accumulation and activities of key enzymes involved in starch synthesis. Starch accumulation and related enzyme activities were investigated in two winter wheat varieties, JM20 and BY535, differing in grain starch content, under two irrigation patterns. Results showed that soil water deficit led to an increase at early grain filling and decrease during late grain filling in starch accumulation rate (SAR) and activities of key enzymes involved in starch synthesis, especially AGPase, SSS and SBE. Water deficit enhanced grain starch accumulation in two wheat cultivars, suggesting that rainfed treatments increase physiological activities during early grain filling and promote starch accumulation. Furthermore, the change of SAR is consistent with SuSy, AGPase, SSS and GBSS. The results suggest that these enzymes play a key role in starch synthesis, and the decrease of photosynthate produced in the source organ is not the factor inhibiting starch accumulation.

48

Jo, Seong-Min, Shuai Jiang, Robert Graf, Frederik R. Wurm e Katharina Landfester. "Aqueous core and hollow silica nanocapsules for confined enzyme modules". Nanoscale 12, n. 47 (2020): 24266–72. http://dx.doi.org/10.1039/d0nr07148j.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

49

Wang, Shan, e Hai Deng. "Peculiarities of promiscuous l-threonine transaldolases for enantioselective synthesis of β-hydroxy-α-amino acids". Applied Microbiology and Biotechnology 105, n. 9 (26 aprile 2021): 3507–20. http://dx.doi.org/10.1007/s00253-021-11288-w.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Abstract The introduction of β-hydroxy-α-amino acids (βHAAs) into organic molecules has received considerable attention as these molecules have often found widespread applications in bioorganic chemistry, medicinal chemistry and biomaterial science. Despite innovation of asymmetric synthesis of βHAAs, stereoselective synthesis to control the two chiral centres at Cα and Cβ positions is still challenging, with poor atomic economy and multi protection and deprotection steps. These syntheses are often operated under harsh conditions. Therefore, a biotransformation approach using biocatalysts is needed to selectively introduce these two chiral centres into structurally diverse molecules. Yet, there are few ways that enable one-step synthesis of βHAAs. One is to extend the substrate scope of the existing enzyme inventory. Threonine aldolases have been explored to produce βHAAs. However, the enzymes have poor controlled installation at Cβ position, often resulting in a mixture of diastereoisomers which are difficult to be separated. In this respect, l-threonine transaldolases (LTTAs) offer an excellent potential as the enzymes often provide controlled stereochemistry at Cα and Cβ positions. Another is to mine LTTA homologues and engineer the enzymes using directed evolution with the aim of finding engineered biocatalysts to accept broad substrates with enhanced conversion and stereoselectivity. Here, we review the development of LTTAs that incorporate various aldehyde acceptors to generate structurally diverse βHAAs and highlight areas for future developments. Key points • The general mechanism of the transaldolation reaction catalysed by LTTAs • Recent advances in LTTAs from different biosynthetic pathways • Applications of LTTAs as biocatalysts for production of βHAAs

50

Kinami, Yoshio, Ichiro Kita, Yasuhiko Kojima e Shigeki Takashima. "Pancreatic Exocrine Enzymes and Intrapancreatic Protein Synthesis in Acute Oedematous Pancreatitis". HPB Surgery 8, n. 1 (1 gennaio 1994): 43–48. http://dx.doi.org/10.1155/1994/25496.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Abstract (sommario):

Changes in serum and intrapancreatic enzyme content and protein synthesis in pancreas were studied in acute oedematous pancreatitis (AOP). Male Wistar rats (n = 111) were divided into 2 groups, controls with a sham operation and those with AOP. Serum amylase levels rose immediately after the procedure causing AOP and then fell gradually, while serum lipase and ribonuclease levels remained higher than control values over 48h. (p < 0.05, 0.01). Serum deoxyribonuclease (DNase) II levels were unchanged. Intrapancreatic enzyme levels were scarcely affected by AOP. 3H-leucine uptake into pancreatic tissue of rats with AOP was decreased throughout the study (p < 0.001), but some protein synthesis continued. Intrapancreatic enzyme contents are maintained despite diffusion into the blood because the pancreas retain its ability to synthesize enzymes.

Articoli di riviste sul tema "Enzymes Synthesis"

Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili