Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.5.1.47 (cysteine synthase)
 625 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Glutathione (GSH) and GSH-related enzymes, glutathione reductase (GR), gamma-glutamyl cysteine synthetase (gamma-GCS), gamma-glutamyl transpeptidase (gamma-GTP), glutathione S-transferase (GST) and adenosine triphosphatase (ATPase) enzymes were analysed to study the effect of busulfan on the defence mechanisms of the lens. All these enzymes were found to increase significantly except GSH which showed only 7.9% increase as compared to controls in precataractous stage. These results affirm that busulfan is capable of evoking a response from the enzymes involved in the various pathways of GSH enabling the lens to prolong its clarity. The cataractous lenses showed significant decrease in all these parameters. Here, the impairment of the defense mechanism (GST, GR) and the total ATPase may be attributed to the cumulative action of the drug which can react with -SH groups of these enzymes, ultimately causing opacification.
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PMID:Glutathione and glutathione-related enzymes in busulfan treated rat lens. 191 43

A number of enzyme systems are important in the protection of cells from chemical-induced oxidative damage. Little is known of the relative importance of these enzymes during postnatal development and its is possible that changes in their activity during this period may alter the susceptibility to toxic agents. This study investigated the activities of glutathione peroxidase, glutathione reductase, catalase, superoxide dismutase, gamma-glutamyl-cysteine synthetase and glutathione synthetase in the liver, lung and kidney of postnatal and adult mice. The first 3 postnatal weeks are characterized by marked changes in the activities of enzymes that protect against oxidative stress (glutathione peroxidase/reductase, catalase and superoxide dismutase). Overall, the activity of these enzymes suggests that the mouse has a higher level of protection against peroxides at various stages during this period but lower capacity to detoxify superoxide anions. The activities of the glutathione-synthetic enzymes (gamma-glutamylcysteine synthetase and glutathione synthetase) were significantly lower in the kidney of the postnatal mice, but the liver and lung had levels similar to those in the adult. Glutathione turnover in the liver of 2-week-old mice was not different from that in adults. The results indicate a complex pattern of development in the activities of detoxification enzyme systems during postnatal development.
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PMID:Postnatal development of enzyme activities associated with protection against oxidative stress in the mouse. 196 50

cDNA clones coding for hemoprotein H-450 were isolated from a rat liver cDNA library using anti-H-450 antibody. The molecular weight calculated from the deduced amino acid sequence comprising 547 amino acid residues was 60,085. The N-terminal sequence and a partial internal amino acid sequence of purified H-450, which were determined chemically, were both found in the amino acid sequence of H-450 deduced from the nucleotide sequence. H-450 mRNA is expressed in liver, kidney, and brain. A homology search of amino acid sequences indicated that H-450 shows no homology with cytochrome P-450, but shows significant homology with bacterial O-acetylserine (thiol)-lyases. However, H-450 has no O-acetylserine (thiol)-lyase activity.
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PMID:Molecular cloning and sequence analysis of cDNA coding for rat liver hemoprotein H-450. 208 36

The gene coding for O-acetylserine sulfhydrylase (OASS) from E. coli K12 was cloned into the vector pBR322 plasmid and expressed in a cysk mutant strain of E. coli that is deficient in O-acetylserine sulfhydrylase (OASS-). The clone containing the OASS gene was selected by using tetracycline-ammonium bismuth citrate medium. Retransformation of the hybrid plasmid into competent cysk mutant cells resulted in the recovery of a clone containing normal levels of O-acetylserine sulfhydrylase. Negative selection of retransformed cysk cells on 1,2,4-triazole plates resulted in the complete inhibition of growth indicating the presence of a functional OASS gene. The ability of the new clone to convert azide to its mutagenic metabolite was tested. Cultures of the clone cells containing significant levels of OASS activity were able to produce a mutagenic product from azide and O-acetylserine as tested on Salmonella typhimurium TA1530. This cloning method could be applied also to clone the same gene from eukaryotic sources.
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PMID:Cloning of the E. coli O-acetylserine sulfhydrylase gene: ability of the clone to produce a mutagenic product from azide and O-acetylserine. 212 44

Among sulfur compounds, thiosulfate and polythionates are present at least transiently in many environments. These compounds have a similar chemical structure and their metabolism appears closely related. They are commonly used as energy sources for photoautotrophic or chemolithotrophic microorganisms, but their assimilation has been seldom studied and their importance in bacterial physiology is not well understood. Almost all bacterial strains are able to cleave these compounds since they possess thiosulfate sulfur transferase, thiosulfate reductase or S-sulfocysteine synthase activities. However, the role of these enzymes in the assimilation of thiosulfate or polythionates has not always been clearly established. Elemental sulfur is, on the contrary, very common in the environment. It is an energy source for sulfur-reducing eubacteria and archaebacteria and many sulfur-oxidizing archaebacteria. A phenomenon still not well understood is the 'excessive assimilatory sulfur metabolism' as observed in methanogens which perform a sulfur reduction which exceeds their anabolic needs without any apparent benefit. In heterotrophs, assimilation of elemental sulfur is seldom described and it is uncertain whether this process actually has a physiological significance. Thus, reduction of thiosulfate and elemental sulfur is a common but incompletely understood feature among bacteria. These activities could give bacteria a selective advantage, but further investigations are needed to clarify this possibility. Presence of thiosulfate, polythionates and sulfur reductase activities does not imply obligatorily that these activities play a role in thiosulfate, polythionates or sulfur assimilation as these compounds could be merely intermediates in bacterial metabolism. The possibility also exists that the assimilation of these sulfur compounds is just a side effect of an enzymatic activity with a completely different function. As long as these questions remain unanswered, our understanding of sulfur and thiosulfate metabolism will remain incomplete.
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PMID:Thiosulfate, polythionates and elemental sulfur assimilation and reduction in the bacterial world. 212 94

An improved method for purifying O-acetylserine sulfhydrylase from Salmonella typhimurium is described as well as a new computer-controlled assay making use of the sulfide ion selective electrode. The purification method uses gradient elution from Q-Sepharose Fast Flow and phenyl-Sepharose columns to give 75 mg (50% yield) of the enzyme starting from 300 g of starting material in 3 days. The sulfide electrode assay makes use of sulfide and calomel electrodes attached to a signal buffer which serves as an impedance match. The output of the signal buffer is linked in parallel to a strip chart recorder and a Keithley Model 575 data acquisition and control system. The system 575 is interfaced to a Packard-Bell AT computer. In addition, two BASIC computer programs have been written to convert potential measured by the electrode to sulfide concentration and to convert the time course data to rates.
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PMID:A rapid purification procedure and computer-assisted sulfide ion selective electrode assay for O-acetylserine sulfhydrylase from Salmonella typhimurium. 215 86

Five independently isolated glutathione-deficient (gsh-) mutants of Saccharomyces cerevisae with maximally 6% residual glutathione content have been analysed genetically. Complementation as well as tetrad analysis of the homo- and heterozygous diploids constructed by suitable crosses of the five mutants indicated that all isolates belong to one complementation group and hence represent different alleles of one gene, GSH1. In order to determine the Gsh1 gene product an assay suitable for yeast was developed to determine the activity of gamma-glutamyl-cysteine synthetase catalysing the first step of glutathione biosynthesis. All mutants are severely deficient in gamma-glutamyl-cysteine synthetase (less than 6.5% of the activity of the glutathione competent parental strain) which is in good accordance with the genetic data.
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PMID:Genetic and biochemical analysis of glutathione-deficient mutants of Saccharomyces cerevisiae. 218 10

The nucleotide sequence of the sulfate and thiosulfate transport gene cluster has been determined and located 3' to the gene (cysP) encoding the thiosulfate-binding protein. Four open reading frames, designated cysT, cysW, cysA, and cysM, have been identified. Similarities in primary structure were observed between (i) the deduced amino acid sequences of CysT and CysW with membrane-bound components of other binding protein-dependent transport systems, (ii) that of the CysA sequence with the "conserved" component of such systems, and (iii) that of the CysM sequence with O-acetylserine sulfhydrylase A (cysK gene product) and the beta-subunit of tryptophan synthase (coded by trpB). Expression of the four genes was analyzed in the T7 promoter-polymerase system.
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PMID:Sulfate and thiosulfate transport in Escherichia coli K-12: nucleotide sequence and expression of the cysTWAM gene cluster. 218 58

We have studied the effect of glutathione reduction by buthionine sulfoximine (BSO), a specific inhibitor of gamma -glutamyl cysteine synthetase, on DNA repair after cisplatin damage in an ovarian cancer cell line with in vitro induced resistance to cisplatin. In addition, we have examined the effect of aphidicolin, a specific inhibitor of DNA polymerase alpha, in combination with BSO on cisplatin-associated DNA repair. BSO treatment was found to partially inhibit DNA repair, and the addition of aphidicolin caused nearly a 100% inhibition in DNA repair activity. Treatment of cells with glutathione ester after BSO resulted in complete recovery of DNA repair activity or partial recovery if aphidicolin was present. The significance of these results to the chemosensitizing effects of BSO medicated glutathione reduction is discussed.
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PMID:Effect of glutathione on DNA repair in cisplatin-resistant human ovarian cancer cell lines. 249 24

A number of metabolizing systems are measured in normal, preneoplastic and neoplastic mouse mammary tissues derived under three different conditions. These biochemical functions are considered to be important in the activation and detoxification of carcinogens and other xenobiotics and have been linked to the process of rat liver hepatocarcinogenesis. The cytochrome P450-dependent enzyme aminopyrine N-demethylase, consistently depressed in hepatocarcinogenesis models in mouse and rat, does not show a significant change among normal, preneoplastic and neoplastic mammary tissues. Glutathione and the enzymes of glutathione metabolism and utilization (e.g. glutathione-S-transferases and gamma-glutamyl transferase), active in the detoxification of xenobiotics, show no significant differences in carcinogen-induced tumors or in their homologous preneoplasias compared to control tissue. There is no increase in the anionic glutathione-S-transferase, a principal marker in rat hepatocarcinogenesis. The only observed biochemical change was a significant decrease in gamma-glutamyl cysteine synthetase the glutathione synthetic enzyme, in the carcinogen-induced preneoplastic and neoplastic line compared to control. Also inorganic glutathione peroxidase was lower in the preneoplastic, but not in the neoplastic tissues.
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PMID:Biochemical characteristics of mouse mammary tissues, preneoplastic lesions and tumors. 257 78


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