Cleavage of atrial natriuretic peptide by a kidney membrane-bound carboxypeptidase A
A Michel1, J Nortier, A Humblet
1Laboratoire de Chimie Biologique, Université de Mons-Hainaut, Mons, Belgium.
Abstract:
An enzymatic activity that cleaved the C-terminal Tyr of ANP (1-28) was characterized in human kidney microvillar membranes by using 125I-labeled rat ANP as substrate. This activity was inhibited by potato carboxypeptidase inhibitor (PCI) and 1.10 phenanthroline, suggesting that it corresponded to a metallo-carboxypeptidase. Solubilization experiments indicated that the carboxypeptidase activity could be recovered in the supernatant after 1% Triton X-100 extraction. As separation by ion exchange chromatography revealed several peaks of enzyme activity, PCI coupled to Sepharose was used for purification. This step resulted in a single protein band at 30 kDa, as analyzed by SDS-PAGE.
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