ASYMMETRIC HYDROLYSIS OF RACEMIC PARA-NITROSTYRENE OXIDE USING AN EPOXIDE HYDROLASE PREPARATION FROM ASPERGILLUS-NIGER

A lyophilized epoxide hydrolase preparation was isolated from the fung us Aspergillus niger. The preparation could be used in place of the wh ole mycelium as biocatalyst for the enantioselective hydrolysis of rac emic para-nitrostyrene oxide. The cosolvent used for substrate dissolu tion showed slightly different effects on enzyme activity and stabilit y. Dimethylsulfoxide (DMSO) was selected as the less inhibitory cosolv ent among those tested. The enzyme preparation was first proved effici ent by running a batch reactor at a low substrate concentration of 4 m M. The hydrolysis of para-nitrostyrene oxide was fast (around 5 h) and with high enantioselectivity (E = 41). The (S) enantiomer of the epox ide remained in the reaction mixture with an enantiomeric excess (ee) higher than 97% for a conversion of 47%. The substrate concentration h ad been optimized. It could be increased to 330 mM (54 g l(-1)) withou t affecting the ee; therefore, the method is potentially useful for th e preparative resolution of epoxides. Applications are in the field of chiral synthons which are important building blocks in organic synthe sis. (C) 1997 by Elsevier Science Inc.