Figure 2. Synthesis of d-alanine from alanine amide HCl by the cells of E. coli JM109/pC138DP. The reaction mixture contained various amounts of racemic alanine amide HCl, washed E. coli cells harvested from 2.0 mL of culture broth, and 50 imol of tris(HCl), pH 8.0, in a total volume of 2.0 mL. The enzyme activity shown by the E. coli transformant was 288,000 Units per liter of culture. The mixtures were incubated at 30 °C. Formation of d-alanine from d-alanine amide is shown as yield (%).
function, structure, and application to the D-stereospecific hydrolysis of racemic amino acid amides and the formation of peptide bonds. A new enzyme, alkaline D-peptidase, acting on a synthetic peptide, (D-Phe)4, was also isolated from Bacillus cereus. We describe its structure and function, as well as its application to the synthesis of D-phenylalanine oligomers. We propose that these two enzymes are new members of the group of penicillin-recognizing enzymes.
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