Purification and properties of an amidase from Rhodococcus erythropolis MP50 which enantioselectively hydrolyzes 2-arylpropionamides

An enantioselective amidase from Rhodococcus erythropolis MP50 was purified to homogeneity, The enzyme has a molecular weight of about 480,000 and is composed of identical subunits with molecular weights of about 61,000. The NH2-terminal amino acid sequence was significantly different from previously published sequences of bacterial amidases, The purified amidase hydrolyzed a wide range of aliphatic and aromatic amides. The highest enzyme activities were found with amides carrying hydrophobic residues, such as pentyl or naphthoyl. The purified enzyme converted racemic 2-phenylpropionamide, naproxen amide [2-(6-methoxy-2-naphthyl)propionamide], and ketoprofen amide [2-(3'-benzoylphenyl)propionamide] to the corresponding S-acids with an enantiomeric excess of >99% and an almost 50% conversion of the racemic amides. The enzyme also hydrolyzed different alpha-amino amides but without significant enantioselectivity.