No abstract

Abstract.The gene for D-aminopeptidase from Ochrobactrum anthropi SCRC C1-38 was cloned in Escherichia coli JM109. An expression plasmid pC138DP (4.5 kb) was constructed. The amount of the enzyme in a cell-free extract of E. coli JM109/pC138DP was elevated up to 288000 units/liter culture, which is about 3600-fold over that of 0. anthropi SCRC C1-38. It was calculated that the enzyme comprised about 30% of the total extractable cellular protein. The intact cells of the E. coli transformant were used as a catalyst for (R)-stereospecific hydrolysis of several racemic amino amides HC1. Complete hydrolysis of (R)-alanine amide was achieved in a short time (44 h) from 5.OM racemic alanine amide HCI using cells of the E. coli transformant. The concentration of (R)-alanine reached 220 g/l. The cells or the cell-free extract catalyzed the synthesis of (R)-2-aminobutyric acid, (R)-methionine, (R)-norvaline and (R)-norleucine from their amides in a similar manner.