O-Acetylserine
O-Acetylserine is an α-amino acid with the chemical formula HO2CCHCH2OCCH3. It is an intermediate in the biosynthesis of the common amino acid cysteine in bacteria and plants. O-Acetylserine is biosynthesized by acetylation of the serine by the enzyme serine transacetylase. The enzyme O-acetylserine -lyase, using sulfide sources, converts this ester into cysteine, releasing acetate: