Abstract
Streptomyces griseus var. alcalophilus was selected because it secreted a unique protease (protease I) that catalyzed the transfer reaction forming the hydroxamic acids of various amino acids. Protease I was purified to the electrophoretically homogeneous state and an activity of more than 125-fold that of the culture broth. The molecular weight of the enzyme was estimated to be 25, 000 by gel filtration. The enzyme was most active in neutral pH for the transfer reaction forming phenylalanine hydroxamic acid, although for the hydrolytic reaction with casein as substrate it was most active in alkaline pH. The enzyme was inhibited by diisopropylfluorophosphate. Protease I catalyzed the transfer reaction synthesizing the hydroxamic acids of hydrophobic, acidic, basic, and small aliphatic amino acids such as Phe, Tyr, Leu, Asp, Glu, Arg, Lys, Ala, and Gly. These results indicate that protease I has broad donor specificity. It is also considered that protease I is a unique enzyme with transfer activity, and distinct from the alkalophilic proteinase reported previously [Yamamoto et al., Agric. Biol. Chem., 38, 37 (1974)].
