A Novel esterase from Pseudochrobactrum asaccharolyticum WZZ003: Enzymatic properties toward model substrate and catalytic performance in chiral fungicide intermediate synthesis

Only a few esterases have been used for the synthesis of optically pure fungicide. For example, ( R )-metalaxyl synthesized using esterase-involved bioreaction displays fungicide activity, whereas ( S )-enantiomer is redundant. However, the biosynthesis of ( R )-metalaxyl is currently hampered by the lower activity, selectivity and thermostability of esterase. Therefore, to obtain a better biocatalyst, several esterase genes were cloned from Pseudochrobactrum asaccharolyticum WZZ003. The esterase PAE07, among eight enzymes, was selected because it exhibited the highest hydrolysis activity toward ( R , S )-DMPM. The DNA and amino acid sequence analysis suggested that PAE07 is a new member of lipolytic enzyme family V. The enzymatic properties of PAE07 toward ( R , S )-DMPM and model substrate ( p- nitrophenyl acetate) were investigated. PAE07 was found to be a highly active esterase with excellent enantioselectivity . The reaction conditions including temperatureand pH were optimized, and the effects of metal ions, organic solvents and detergents were also investigated. Results indicated that PAE07 is a competitive candidate for ( R )-metalaxyl manufacturing.