FIRST STEREOSELECTIVE SYRTRESIS OF D-AMINO ACID

The first stereoselective synthesis of D-amino acid N- alkyl amides was achieved by the use of D-aminopeptidase from Ochrobactrum anthropi. The enzyme immobilized by urethane prepo- lvmer PU-6 catalyzed aminolvsis reaction of racemic amino acid esters in organic solvents.- Enzymes are useful as catalysts for the preparation of optically active compounds', because they are chiral at the active center, which distinguish- es stereochemical differences of reactants. Conventional chemical synthesis generally lacks stereoselectivity and requires expensive catalysts and sub- strates for a large scale production of an optically active compound2. The use of proteases in the formation of a peptide bond is an alter- 3 native to the chemical methods . D-amino acid containing peptides have recently been noticed for their interesting biological activityl. Only a limited knowledge has been available about enzymes specific for D-amino acid containing peptides, and none of them has been used for peptide or amide synthesis, although nonstereospecific enzymatic syntheses of such peptides have been reported5. These synthetic procedures require expensive D-amino acid derivatives because of the inherent nonstereoselectivity. Recently, we aimed to synthesize an amide bond D-stereoselectively by the use of an en- zyme, and started a screening program for a new enzyme. We succeeded in isolating a bacterium Ochrobactrum anthropi (formerly Achromobacter sp.)