Participation in Digestion by the Proteolytic Enzymes of the Posterior Salivary Gland in Octopus-IV

Purification and Some Properties of Proteolytic Enzymes from the Digestive Juice

Abstract

Four proteolytic enzymes (Enzymes I to IV) were separated by Sephadex gel filtration and CM-Sephadex chromatography from the digestive juice. Enzymes III and IV, when further purified respetively by rechromatography and by preparative disc electrophoresis, were found to be electrophoretically homogeneous.
The three enzymes I, II and III, although differeing somewhat in pH-stability and isoelectric point, were basic proteins with molecular weight of approximately 21, 000 and had many similarities to carboxypeptidase A in enzymic properties. From these results it was clear that all these enzymes were cationic carboxypeptidase A. In addition, it was found that Enzyme III agreed closely in some properties with the posterior salivary gland carboxypeptidase A dealt with in the previous paper.
On the other hand, Enzyme IV, like chymotrypsin and the like, hydrolyzed benzoyland acetyl-L-tyrosine ethyl esters but, unlike them, did not act on amides such as glycyl-L-phenylalanine amide at all. The enzyme, however, had some similarities to chymotrypsin A in enzymic properties. Thus the enzyme appeared to be a closely related proteinase such as chymotrypsin A. In addition, it was found that the enzyme agreed closely in enzymic properties with Enzymes I, II and III of the posterior salivary gland, but differed from them in physicochemical properties such as isoelectric point and molecular weight.