Degradation of atrial natriuretic factor by kidney cortex membranes. Isolation and characterization of the primary proteolytic product.
Synthetic rat atrial natriuretic factor (r-ANF, 1-28) was incubated with rat kidney cortex membranes, and a predominant degradation product was identified by reverse-phase high performance liquid chromatography. The degradation product was subjected to amino acid analyses and found to have a composition identical to r-ANF. Amino-terminal sequence analyses identified two distinct amino-terminal residues and suggested that cleavage had occurred between the cysteine-phenylalanine bond (residues 7 and 8) of r-ANF. This degradative process could be inhibited by 1,10-phenanthroline and EDTA, suggesting that the enzyme responsible for proteolysis is a metalloendoprotease. The enzyme exhibits a Michaelis-Menten constant of approximately 10 microM for the metabolism of r-ANF and has a broad pH optimum between 8.5 and 9.5. These findings suggest that ANF may be initially degraded in the kidney at a single cleavage site within the 17-residue ring structure.
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D006863:Hydrogen-Ion Concentration; D007672:Kidney Cortex / Q000378:metabolism*; D007700:Kinetics; D008566:Membranes / Q000378:metabolism; D009994:Osmolar Concentration; D010446:Peptide Fragments / Q000032:analysis*; D051381:Rats
D000596:Amino Acids; D010446:Peptide Fragments; D009320:Atrial Natriuretic Factor