METHOD FOR ENZYMATIC SYNTHESIS OF BRIVARACETAM CHIRAL INTERMEDIATE

Disclosed is a method for enzymatic synthesis of a brivaracetam chiral intermediate, i.e., a method for synthesizing a brivaracetam chiral intermediate (R)-3-cyanohexanoic acid by catalyzing the hydrolysis of 3-cyanohexanitrile using an enzyme with nitrile hydrolysis activity, and the enzyme with nitrile hydrolysis activity is obtained by carrying out a single mutation or a double mutation on an amino acid at position 140 or an amino acid at position 175 in an amino acid sequence as set forth in SEQ ID NO. 2. Compared with a wild type, the nitrilase mutant of the present invention has the activity increased by 10 times, an ee value increased to 300 or more from 39, a substrate conversion rate of 45%, and a product ee which can reach 98.5%, and the yield of (R)-3-aminomethylhexanoic acid by catalytic hydrogenation synthesis using (R)-3-cyanohexanoic acid reaches 85% or more. The present invention features a short synthesis route, mild reaction conditions, and high atom economy, and can be applied to the indust