Publication： Journal of American Chemical Society

Date of Publication: May 6, 2009

Authors： Eugene Antipov, Art E. Cho, and Alexander M. Klibanov

DOI 10.1021/ja903482u

The effect of all possible mutations at position 178 on the enantioselectivity of yeast surface bound horseradish peroxidase (HRP) toward chiral phenols has been investigated. In contrast to their wildtype predecessor, most HRP mutants are enantioselective, with the Arg178Glu variant exhibiting the greatest, 25-fold, (S)/(R) preference. Using kinetic analysis of enzymatic oxidation of various substrate analogues and molecular modeling of enzyme-substrate complexes, this enantioselectivity enhancement is attributed to changes in the transition state energy due to electrostatic repulsion between the carboxylates of the enzyme’s Glu178 and the substrate’s (R)-enantiomer.