Purification and properties of acyltransferases from Pseudomonas aeruginosa

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Abstract
Two preparations of amidase, of similar final specific activities, were obtained from P. aeruginosa 8603/A grown on acetate plus NH., and on acetamide, as C and N sources. The purified enzymes catalyzed the transfer of the acylmoieties of a number of aliphatic amides to water (amidase activity) and to hydroxylamine (amide-transferase activity); they also catalyzed to a smaller extent the transfer to hydroxylamine of the acylmoieties of several aliphatic acids (acid-transferase activity). Both enzymes exhibited the same substrate specificity. The ratios of the amidase, amide-transferase and acid-transferase activities of each enzyme varied in an identical manner with different substrates. Both enzymes exhibited identical kinetic properties. The amidase activity of both enzymes was non-competitively inhibited by urea (Ki1-1 m[image]) and N-methylurea; these inhibitions were reversed by hydroxylamine. Thiourea did not inhibit. The amide-transferase and acid-transferase activities of both enzymes were inhibited by iodoacetate and p-hydroxy-mercuribenzoate: the inhibition caused by the latter compound was reversed by cysteine. Both activities were inhibited by low concentrations of fluoride in the presence but not in the absence of hydroxylamine. The enzyme from cells grown on acetamide was identical with that from cells grown on acetate. The properties of the enzyme were those of an acyltransferase, in which acyl-enzyme complexes were split by hydroxylamine or water.

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