Studies on Proteolytic Enzymes (Pronase) of Streptomyces griseus K-I

III. Purification and Proteolytic Specificity of Alkaline Proteinase C from Pronase

Abstract

The purification of DFP-sensitive alkaline proteinase C from pronase is described. When the proteolytic specificity of alkaline proteinase C was investigated using the reduced, carboxymethylated phenylalanyl chain of insulin, angiotensin II, and oxytocin as substrates, nine splittings in the first substrate and two splittings in the second and third substrates were detected, respectively.
In the reduced, carboxymethylated phenylalanyl chain of insulin, more than 30% hydrolysis of the bonds Leu (11)-Val (12), Tyr (16)-Leu (17), and Phe (25)-Tyr (26) was found. Additional cleavages (less than 20%) of the bonds Phe (1)-Val (2), Gln (4)-His (5), Leu (15)-Tyr (16), Leu (17)-Val (18), and Phe (24)-Phe-(25) were also noted. Hydrolysis of angiotensin II and oxytocin was observed at Tyr (4)-Ile (5) in the former and Leu (8)-GlyNH₂ (9) in the latter substrate. The specificity of Streptomyces griseus alkaline proteinase C was compared with those of other DFP-sensitive alkaline proteinases.