Acts on many kinds of nitrile compounds such as aliphatic, aromatic, and heterocyclic mononitriles or dinitriles. Prefers S-(-)-2-(4'-isobutylphenyl)-propionitrile to R-(+)-2-(4'-isobutylphenyl)-propionitrile as the substrate. a nitrile + 2 H2O = a carboxylate + NH4(+) Belongs to the carbon-nitrogen hydrolase superfamily. Nitrilase family.