1 N-Acetylglutamate synthetase (acetyl-CoA: l-glutamate N-acetyltransferase), the first enzyme of arginine biosynthesis, has been detected in extracts from Pseudomonas aeruginosa by a specific and sensitive assay in vitro.
2 The enzyme, partially purified by chromatography on hydroxyapatite, was dependent on l-glutamate and acetyl-CoA. l-Aspartate could not replace l-glutamate as a substrate; acetyl phosphate and N2-acetyl-l-ornithine were not utilized as acetyl donors.
3 The enzyme was inhibited by l-arginine (approx. 50% inhibition by 0.1 mM l-arginine). N2-Acetyl-l-ornithine, l-ornithine, and l-citrulline were not effective as inhibitors. Since N-acetylglutamate 5-phosphotransferase of P. aeruginosa is known to be inhibited by arginine, the first and the second enzymes of arginine synthesis in this organism are subject to feedback inhibition by the end-product.
4 Arginine did not repress the formation of N- acetylglutamate synthetase.