Carboxypeptidase-Type Kininase of Human Kidney and Urine

Abstract

Abstract

A carboxypeptidase was partially purified from human urine and a similar or identical enzyme was extracted from a particulate fraction of the human kidney. The enzyme cleaved basic C-terminal amino acids of peptides including bradykinin. The inhibition of the human renal/urinary carboxypeptidase was different from that of plasma carboxypeptidase N (kininase I) or pancreatic carboxypeptidase B. The urinary enzyme was not affected by inhibitors of catheptic enzymes or kininase II and has no carboxypeptidase A activity. The urinary/renal carboxypeptidase had a molecular weight of 40,000. The urinary carboxypeptidase did not cross-react with antiserum to human pancreatic carboxypeptidase B. These properties distinguish carboxypeptidase of human urine and kidney from plasma carboxypeptidase N and from pancreatic carboxypeptidase B.