O-Acetylserine sulfhydrylase-B (OASS-B, EC 18.104.22.168) is one of the two isozymes produced by Escherichia coli that catalyze the synthesis of l-cysteine from O-acetyl-l-serine and sulfide. The cysM gene encoding OASS-B was cloned and the enzyme was overexpressed in E. coli using pUC19 with a lacUV5 promoter. The enzyme was purified to homogeneity, as evidenced by SDS-PAGE. Approximately 300 mg of purified OASS-B was obtained from 1600 mL of culture broth with a purification yield of 60% or higher. The purified OASS-B was characterized and its properties compared with OASS-A. OASS-B did not form a complex with E. coli serine acetyltransferase (SAT, EC 22.214.171.124) and showed a wide range of substrate specificity in nonproteinaceous amino acid synthesis.
- Cysteine synthase
- Nonproteinaceous amino acid
- O-Acetylserine sulfhydrylase-B
- Recombinant Escherichia coli
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