Transformation of aliphatic and aromatic nitriles by a nitrilase from Pseudomonas sp.

A Pseudomonas sp. (S1) isolated from a garden soil possessed a unique nitri lase, which is capable of catalyzing the direct hydrolysis of both potassiu m and organic cyanides to their corresponding carboxylic acids and ammonia, without the formation of amide as an intermediate. The nitrilase was purif ied with 4.8% recovery in three steps from a cell extract of the strain. Th e relative mobility of the homogenous enzyme preparation in SDS and native polyacrylamide gels indicated molecular weight of 41 kDa, approximately. Ps eudomonas sp. (81) utilized all the nitriles as carbon and nitrogen sources . The enzyme was induced by both aliphatic and aromatic nitriles, while the aliphatic olefinic nitrile - acrylonitrile was the most suitable substrate . The nitrilase also catalyzed the hydrolysis of acetonitrile, adiponitrile , benzonitrile, butyronitrile, glutaronitrile, phenylacetonitrile, succinod initrile, and potassium cyanide, with the formation of ammonia and the corr esponding carboxylic acids. The Michaelis-Menten constant, K-m, of the part ially purified nitrilase for acetonitrile, acrylonitrile, adiponitrile, ben zonitrile, and potassium cyanide presented values of 11.26, 5.88, 10.28, 12 .27, and 0.75 mM, respectively.