Efficient expression in E-coli of an enantioselective nitrile hydratase from Rhodococcus erythropolis

摘要

The genes encoding an enantioselective nitrile hydratase (NHase) from Rhodococcus erythropolis AJ270 have been cloned and an active NHase has been produced in Escherichia coli. Maximal activity was found when the genes encoding the alpha- and beta-subunits were transcribed as one unit and the gene encoding the P44k activator protein as a separate ORF on a single replicon. Addition of n-butyric acid and FeSO4 could improve NHase activity. Coexpression of the GroEL-GroES chaperone proteins increased activity in the absence of P44k protein but had no effect in the presence of P44k. The recombinant enzyme was highly enantioselective in the synthesis of S-(+)-3-benzoyloxy- 4-cyanobutyramide from the prochiral substrate 3-benzoyloxyglutaronitrile.