title: Kinin cleavage by human erythrocytes.
abstract: An aminopeptidase-P has been purified 230-fold from human erythrocytes. The purified enzyme cleaved arginine from des-(Arg9)-bradykinin (Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe) had a molecular weight in nondenaturing buffers of 155,000 +/- 6,900 daltons, was not inactivated by chelating agents, had a pH optimum of 7.2, and was stimulated by manganous ions. The aminopeptidase-P was stable in intact erythrocytes for at least 21 days. Extensively washed and intact human erythrocytes cleaved arginine from exogenously supplied des-(Arg9)-bradykinin; arginine was the earliest-appearing reaction product. Purified aminopeptidase-P also cleaved a group of X-proline dipeptides including leucyl-proline, methionyl-proline, phenylalanyl-proline, arginyl-proline, and alanyl-proline. The total intra-erythrocytic aminopeptidase-P activity of the "average 70-kg man" was 2,600 units, approximately five times the amount of activity in the total lung mass. The human erythrocyte aminopeptidase-P activity was not tightly bound to the erythrocyte membrane. Intact erythrocytes also exhibited some kinin-converting enzyme activity.
mesh_terms: D000626:Aminopeptidases / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology; D001120:Arginine / Q000378:metabolism; D001920:Bradykinin / Q000031:analogs & derivatives / Q000378:metabolism; D004151:Dipeptides / Q000378:metabolism; D004492:Edetic Acid / Q000494:pharmacology; D004789:Enzyme Activation; D004910:Erythrocyte Membrane / Q000201:enzymology; D004912:Erythrocytes / Q000201:enzymology / Q000502:physiology*; D005260:Female; D006801:Humans; D007705:Kinins / Q000378:metabolism*; D008297:Male; D008670:Metals / Q000494:pharmacology; D010446:Peptide Fragments / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D004151:Dipeptides; D007705:Kinins; D008670:Metals; D010446:Peptide Fragments; C024626:bradykinin, des-Arg(9)-; D001120:Arginine; D004492:Edetic Acid; D000626:Aminopeptidases; C022750:X-Pro aminopeptidase; D001920:Bradykinin