Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:4.2.1.22 (cystathionine beta-synthase)
965 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Four enzymes necessary for the metabolism of methionine by the trans-sulfuration pathway, methionine adenosyltransferase (EC 2.5.1.6), adenosylhomocysteinase (EC 3.3.1.1), cystathionine beta-synthase (EC 4.2.1.22) and cystathionine gamma-lyase (EC 4.4.1.1) were identified in Tetrahymean pyriformis. The ability of these cells to transfer 35S from E135S]methionine to form [35S] cysteine was also observed and taken as direct evidence for the functional existence of this pathway in Tetrahymena. An intermediate in the pathway and an active methyl donor, S-adenosylmethionine, was qualitatively identified in Tetrahymena and its concentration was found to be greater in late stationary phase cells than in early stationary phase cells.
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PMID:The transsulfuration pathway in Tetrahymena pyriformis. 1 63

ATP-sulfurylase, cysteine synthase, homocysteine synthase, arylsulfatase and beta-cystathionase in Saccharomycopsis lipolytica are repressed on the addition of methionine, homocysteine or cysteine to the growth medium. The use of appropriate mutants enabled us to demonstrate that the synthesis of these enzymes is regulated by the system involving at least two low-molecular weight effectors--most likely cysteine and methionine (or their close derivatives).
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PMID:Regulation of s-amino acids biosynthesis in Saccharomycopsis lipolytica. 28 1

The steady-state kinetics of the two substrate reaction of L-cysteine desulfation in the presence of 2-mercaptoethanol catalyzed by serine sulfhydrase from bakers yeast -- a pyridoxal phosphate-containing enzyme of the beta -- substituting lyase type -- were studied. Highly purified enzyme preparations (approximately 90% purity) of Saccharomyces cerevisiae with specific activity of 25 mumoles of H2S per 1 hr per mg of protein were used. The values of V, KS1, KS2 and alpha were calculated from the initial rates of the reaction under constant concentration of L-cysteine (S1) and variable concentration of 2-mercaptoethanol (S2) and vice versa. The data obtained suggest that under conditions of a two-substrate reaction catalyzed by serine sulfhydrase and in case of beta-cyanoalanine synthase of blue lupin the substrate binding to the enzyme is interdependent and obeys a unordered mechanism with o formation of a ternary aminosubstrate-pyridoxal phosphateenzyme-cosubstrate complex (alpha = 2.6).
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PMID:[Steady-state kinetics of reactions catalyzed by serine sulfhydrases of Saccharomyces serevisiae]. 38 Jun 61

Characteristics of a mutant of Cephalosporium acremonium with enhanced potential to utilize sulfate for cephalosporin C production were investigated with sulfur-starved cells. DL-Norleucine showed an inhibitory effect on cephalosporin C and penicillin N production by the mutant in the presence of a sulfur source such as sulfate, sulfite, thiosulfate, and L-cystine, but it exhibited no effect when it was added after a certain period of incubation. On the contrary, antibiotic production by the parent was stimulated by norleucine regardless of the addition time. An increase in the intracellular cysteine pool was found when the cells were incubated with L-methionine or norleucine and sulfate. Enzymatic studies revealed that methionine and norleucine stimulated the cysteine desulfhydrase formation, and this effect was significant in the mutant. Finally the mutant was found to have an enhanced L-serine sulfhydrylase activity. The increase in this enzyme activity in the mutant seems responsible for the increase in the sulfate-utilizing ability and the methionine sensitivity by maintaining a high level of the cysteine pool. Accordingly, the effect of methionine and norleucine is assumed to be exerted through cysteine.
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PMID:Sulfur metabolism of a mutant of Cephalosporium acremonium with enhanced potential to utilize sulfate for cephalosporin C production. 55 69

The cystine content of the protein of a number of different lines of legume seeds has been determined by the method of Krull et al. which selectively reacts cysteine residues of intact, reduced proteins with 2-vinylquinoline, giving an adduct with an absorption maximum at 318 nm. Some seed lines were found to have 3.5 times as much cysteine as the seed line with the lowest cysteine content, perhaps offering opportunities for improvement in the nutritional quality of bean seed proteins through breeding and selections. While no correlation between cysteine levels and protein content was observed, a positive correlation was found between the specific activity of the terminal enzyme of cysteine synthesis, cysteine synthase, and the cysteine content of seeds.
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PMID:Cystine content of legume seed proteins: estimation by determination of cysteine with 2-vinylquinoline, and relation to protein content and activity of cysteine synthase. 92 60

Forteen species (17 strains) of phototrophic bacteria as well as one strain of Thiobacillus denitrificans were tested for cysteine synthase and S-sulfocysteine synthase. All strains contain cysteine sythase active with O-acetylserine; only the Chromatiaceae, two species of the Rhodospirillaceae and T. denitrificans contain S-sulfocysteine synthase. In six species repression by different sulfur compounds in the medium was studied. In Chromatium vinosum, cysteine synthase was found to be constitutive, while in the Rhodospirillaceae tested the enzyme is repressed by sulfide. Thiosulfate had a derepressive effect in Rhodopseudomonas globiformis but strongly repressed cysteine synthase in R. sulfidophila and R. palustris. Cysteine had only moderate effects with the species tested.
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PMID:Cysteine and S-sulfocysteine biosynthesis in phototrophic bacteria. 96 65

O-Acetylserine (thiol) lyase, the last enzyme in the cysteine biosynthetic pathway, was purified to homogeneity from spinach leaf chloroplasts. The enzyme has a molecular mass of 68,000 and consists of two identical subunits of Mr 35,000. The absorption spectrum obtained at pH 7.5 exhibited a peak at 407 nm due to pyridoxal phosphate, and addition of O-acetylserine induced a considerable modification of the spectrum. The pyridoxal phosphate content was found to be 1.1 per subunit of 35,000, and the chromophore was displaced from the enzyme by O-acetylserine, leading to a progressive inactivation of the holoenzyme. Upon gel filtration chromatography on Superdex 200, part of the chloroplastic O-acetylserine (thiol) lyase eluted in association with serine acetyltransferase at a position corresponding to a molecular mass of 310,000 (such a complex called cysteine synthase has been characterized in bacteria). The activity of O-acetylserine (thiol) lyase was optimum between pH 7.5 and 8.5. The apparent Km for O-acetylserine was 1.3 mM and for sulfide was 0.25 mM. The calculated activation energy was 12.6 kcal/mol at 10 mM O-acetylserine. The overall amino-acid composition of spinach chloroplast O-acetylserine (thiol) lyase was different than that determined for the same enzyme (cytosolic?) obtained from a crude extract of spinach leaves. A polyclonal antibody prepared against the chloroplastic O-acetylserine (thiol) lyase exhibited a very low cross-reactivity with a preparation of mitochondrial matrix and cytosolic proteins suggesting that the chloroplastic isoform was distinct from the mitochondrial and cytosolic counterparts.
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PMID:Purification and characterization of O-acetylserine (thiol) lyase from spinach chloroplasts. 137 15

Cysteine synthase (O-acetylserine sulfhydrylase) has been purified to homogeneity from bell pepper (Capsicum annuum) fruit chromoplasts. This enzyme consists of two subunits of 35 kDa. Immunocytochemical localization experiments confirmed the plastid location of this enzyme. A full-length cDNA was isolated from an expression library of C. annuum. The deduced peptide sequence revealed high similarity between the C. annuum cysteine synthase and its bacterial counterparts. In vitro transcription and translation of the cDNA and subsequent import experiments demonstrated that the encoded cysteine synthase is located in the plastids. The steady-state level of the cysteine synthase mRNA is almost constant in dark-grown hypocotyls, leaves, and fruits. However, a slight increase in this mRNA level was detected during fruit development (when the 25 S rRNA was taken as an internal standard). Similarly, the cysteine synthase activity in plastids was found to increase during fruit development and reaches the highest levels in the chromoplasts of red fruits. To address the physiological role of this phenomenon, we have shown that cysteine is engaged in the active metabolism of glutathione. Thus, in connection with the previous demonstration of an active tocopherol metabolism, it is concluded that differentiation of chloroplast to chromoplast in C. annuum involves an active synthesis of potential antioxidants or redox modulators.
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PMID:Cysteine synthase from Capsicum annuum chromoplasts. Characterization and cDNA cloning of an up-regulated enzyme during fruit development. 138 58

Several inherited metabolic disorders of the transsulfuration pathway are discussed. They are hypermethioninemia, homocystinuria, cystathioninuria, beta-mercaptolactate cysteine disulfideuria and sulfite oxidase deficiency (SOD). Primary coverage is given to homocystinuria and SOD. In the case of homocystinuria, metabolic defects include cystathionine beta-synthase deficiency, methylenetetrahydroforate reductase deficiency, and mutations in cobalamin metabolism. Their main clinical pictures, metabolic abnormalities, and treatment are also described. SOD appears in two cases as an isolated enzyme defect and a combined deficiency of sulfite oxidase and xanthine dehydrogenase that share a common molybdenum cofactor. The clinical, biochemical and neurological features of the two disorders are reviewed.
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PMID:[Inherited metabolic disorders of the transsulfuration pathway]. 140 82

Characterization of the physical and catalytic properties of the enzyme responsible for nematode "activated L-serine sulfhydrase" activity (L-cysteine + R-SH-->cysteine thioether + H2S) has led to its identification as a novel, variant form (allelozyme) of cystathionine beta-synthase that is distinct from a mammalian-type synthase also present in nematodes. Additional work has demonstrated the ability of live Panagrellus redivivus to produce H2[35S] from exogenous L-[35S]cysteine and 2-mercaptoethanol, thus providing preliminary evidence for the in vivo operation of the activated L-serine sulfhydrase reaction in nematodes.
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PMID:The identification of a variant form of cystathionine beta-synthase in nematodes. 149 73


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