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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.
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 enzyme cystathionine gamma-lyase converts the cystathionine into cysteine and alpha-ketobutyrate. In plants and bacteria, cysteine biosynthesis also starts from serine, which is converted to O-acetylserine by the enzyme serine transacetylase. The enzyme cysteine synthase, using sulfide sources, converts this ester into cysteine, releasing ...
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
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 ...
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 .
EC 6.3.2.19: The ubiquitinylation process is now known to be performed by several enzymes in sequence, starting with EC 6.2.1.45 (ubiquitin-activating enzyme E1) and followed by several transfer reactions, including those of EC 2.3.2.23 (E2 ubiquitin-conjugating enzyme) and EC 2.3.2.27 (RING-type E3 ubiquitin transferase)
Other names in common use include: β-thionase, cysteine synthase, L-serine hydro-lyase (adding homocysteine), methylcysteine synthase, serine sulfhydrase, and; serine sulfhydrylase. Methylcysteine synthase was assigned the EC number EC 4.2.1.23 in 1961. A side-reaction of CBS caused this. The EC number EC 4.2.1.23 was deleted in 1972. [7]