Renin and kidney cathepsins

At least four proteolytic enzymes, known as kidney cathepsins I, II, III, and IV, were found in crude kidney extracts. In their substrate specificity these intracellular proteinases show similarities to pepsin, trypsin, aminop tidase, and carboxypeptidase, respectively (11). Plentl and Page (139) showed that cathepsins I and IV are not identical with renin. Schales, Holden, and Schales (160) differentiated renin from all four cathepsins. The experimental proof for the nonidentity of renin and kidney cathepsins is summarized in Table IV. 

The earlier literature on cathepsins supplies some additional suggestive evidence for the mmidentity of these four proteinases with renin. 

Cathep- sin Schales, Holden, and Schales (160) Plentl and Pago (130) 

I Not present in Fraction A (157). Precipitate obtained by treating saline extracts of kitmeya with 

III Not present in commercial renin preparation i lOOO (S.M.A. Corp.)  

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