Asymmetric hydrolysis of dimethyl phenylmalonate by immobilized penicillin G acylase from E. coli

This paper reports that penicillin G acylase (PGA) is able to hydrolyze prochiral diethyl and dimethyl phenylmalonate, although activity is higher with the dimethyl ester. The process has two very interesting features: (i) the enzyme is fully specific and did not recognize the monoester as substrate, very likely due to the presence of a charged carboxylic acid in alpha-position, permitting to fully transform the diester in the chiral monoester and (ii) the reaction is almost fully asymmetric, producing (+)-methyl phenylmalonate. Although the activity of PGA against this substrate is lower than against other substrates of PGA (e.g., 20-fold lower than when using (+)-methyl mandelate), the use of a highly loaded biocatalyst (80 mg of PGA per gram of support) permitted to obtain around 80 U/g of biocatalyst, permitting to produce 100 mM (+)-methyl phenylmalonate using 1 g of biocatalyst per 100 ml of reaction volume in only 5 h.