Characterization of a nitrilase from Nocardia sp. (Rhodochrous group) N.C.I.B. 11215, using p-hydroxybenzonitrile as sole carbon source.

The purification and properties of an enzyme from Nocardia sp. which catalyses the conversion of p-hydroxybenzonitrile to p-hydroxybenzoic acid and ammonia without intermediate formation of the amide is described. The enzyme displayed a broad pH optimum between 7.0 and 9.5 and exhibited Michaelis-Menten kinetics with Km of 1.27 mM for p-hydroxybenzonitrile. The 12-unit multimeric enzyme possessed a mol. wt of 560,000 and was sensitive to thiol-specific reagents. Although aliphatic nitriles were not substrates for the enzyme a broad range of substituted aromatic nitriles were attacked with a general preference being shown for those with meta substitution.