Abstract
3-Chloro-D-alanine chloride-lyase, which occurs in the cells of Pseudomonas putida CR 1-1, catalyzes not only the α, β-elimination reaction of 3-chloro-D-alanine to form pyruvate, but also its β-replacement reaction in the presence of a high concentration of sodium hydrosulfide to form D-cysteine. Using the β-replacement reaction, the enzymatic synthesis of D-cysteine by resting cells was investigated. The culture conditions for cell production of the bacterium with high D-cysteine-producing activity and the reaction conditions for D-cysteine production were optimized. Under these optimal reaction conditions, 100% of the added 3-chloro-D-alanine could be converted to D-cysteine and, as the highest yield, 20.6mg of D-cysteine per 1.0ml of reaction mixture could be synthesized.
