The use of an equilibrium between enantiomers of your starting material to enable hydrolysis of more than 50% of a racemic mixture has been a point of keen interest in nitrilase research. The hurdle to it becoming widespread has tended to be that the pH at which racemization occurs at a useful rate tends not to be one that your standard biocatalyst is happy operating at. A newly accepted manuscript into Tetrahedron Letters called “High yield synthesis of D-phenylglycine and its derivatives bynitrilase mediated dynamic kinetic resolution in aqueous-1-octanol biphasicsystem” by Jian Qiua, Erzheng Su, Wei Wang, and Dongzhi Wei is a useful addition to this literature. They use a nitrilase (after citing unpublished data on its enantioselectivity… why unpublished? It looks an interesting nitrilase!) from Sphingomonas wittichii RW1 to get DKR in a biphasic system (buffer/octanol).
