DEGRADATION OF 2-KETOARGININE BY GUANIDINOBUTYRASE IN ARGININE AMINOTRANSFERASE PATHWAY OF BREVIBACTERIUM-HELVOLUM

Guanidinobutyrase (EC 3.5.3.7) involved in the arginine oxygenase path way of Brevibacterium helvolum IFO 12073 was found to catalyze also th e hydrolysis of 2-ketoarginine (2-keto-5-guanidinovalerate) to 2-ketoo rnithine (2-keto-5-aminovalerate) and urea, the second step of the arg inine aminotransferase pathway, No other enzyme that degraded 2-ketoar ginine was found in cells grown on L-arginine, The enzyme hydrolyzed 2 -ketoarginine with a relative rate of about 0.7% of that toward 4-guan idinobutyrate. The K-m for 2-ketoarginine was 33 mM.