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In enzymology, a cysteine synthase (EC 2.5.1.47) is an enzyme that catalyzes the chemical reaction. O 3-acetyl-L-serine + hydrogen sulfide L-cysteine + acetate. Thus, the two substrates of this enzyme are O 3-acetyl-L-serine and hydrogen sulfide, whereas its two products are L-cysteine and acetate.
There are five different structurally related types of PLP enzymes. Members of this family belong to the type I and are: [6] in the transsulfurylation route for methionine biosynthesis: Cystathionine γ-synthase (metB) which joins an activated homoserine ester (acetyl or succinyl) with cysteine to form cystathionine
A number of pyridoxal-dependent enzymes involved in the metabolism of cysteine, homocysteine and methionine have been shown to be evolutionary related. [1] These enzymes are tetrameric proteins of about 400 amino-acid residues. Each monomer has an active site, which however requires the N-terminal of another monomer to be completed (salt ...
The systematic name of this enzyme class is O-acetyl-L-homoserine:methanethiol 3-amino-3-carboxypropyltransferase. Other names in common use include O -acetyl- L -homoserine acetate-lyase (adding methanethiol) , O-acetyl- L -homoserine sulfhydrolase , O -acetylhomoserine (thiol)-lyase , O -acetylhomoserine sulfhydrolase , and methionine synthase .
The plant glutamate cysteine ligase is a redox-sensitive homodimeric enzyme, conserved in the plant kingdom. [26] In an oxidizing environment, intermolecular disulfide bridges are formed and the enzyme switches to the dimeric active state. The midpoint potential of the critical cysteine pair is -318 mV.
L-cysteine production pathways; Reactants → Enzyme Cofactors Notes O-acetyl-L-serine/hydrogen sulfide → cysteine synthase [9] pyridoxal phosphate not present in humans L-cystine/2 glutathione → glutathione-cystine transhydrogenase [10] cystathionine: → cystathionine γ-lyase [4] pyridoxal phosphate 3-mercapto-pyruvate: → cysteine ...
In enzymology, a phosphopantothenate—cysteine ligase also known as phosphopantothenoylcysteine synthetase (PPCS) is an enzyme (EC 6.3.2.5) that catalyzes the chemical reaction which constitutes the second of five steps involved in the conversion of pantothenate to Coenzyme A.
Cystathionine is an intermediate in the synthesis of cysteine from homocysteine. It is produced by the transsulfuration pathway and is converted into cysteine by cystathionine gamma-lyase (CTH). Biosynthetically, cystathionine is generated from homocysteine and serine by cystathionine beta synthase (upper reaction in the diagram below).