Reactions Catalyzed by Amidases

Although the metabolic deamidation of several naturally occurring amides and their analogues, e.g. glutamine (l-4) and nicotinamide (5), has been extensively investigated, it appeared of interest to extend to simpler aliphatic and aromatic derivatives our knowledge of the variety of compounds undergoing enzyme-catalyzed deamidation. Therefore, three compounds, acetamide, butyramide, and benzamide, were chosen as models, and organisms possessing enzymes active in deamidation were readily isolated. Independently, an enzyme from Pseudomonas aeruginosa with activity for acetamide has been reported (6), and relatively crude fractions have been obtained from mycobacteria which are active in the deamidation of a variety of amides (7). This report is concerned with an inducible enzyme obtained from a strain of Pseudomonas Jluwescens active in the deamidation of 2 and 3 carbon primary amides. Our interpretation of the data leads to the suggestion that the enzyme involved, acetamidase, catalyzes the hydrolysis of acetamide (Equations 1 and 2), as well as the transfer of the acyl moiety to hydroxylamine (Equations 1 and 3) by a mechanism involving an acylenzyme complex (Equation 1).