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Kinin cleavage by human erythrocytes
Author(s) -
Sidorowicz W.,
Canizaro Peter C.,
Běhal Francis J.
Publication year - 1984
Publication title -
american journal of hematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.456
H-Index - 105
eISSN - 1096-8652
pISSN - 0361-8609
DOI - 10.1002/ajh.2830170408
Subject(s) - proline , aminopeptidase , arginine , biochemistry , kinin , enzyme , chemistry , bradykinin , molecular mass , cleavage (geology) , microbiology and biotechnology , biology , amino acid , leucine , receptor , paleontology , fracture (geology)
An aminopeptidase‐P has been purified 230‐fold from human erythrocytes. The purified enzyme cleaved arginine from des‐(Arg 9 )‐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‐(Arg 9 )‐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.