Vasopressin-sensitive kidney adenylate cyclase. Structural requirements for attachment to the receptor and enzyme activation: studies with vasopressin analogues

Abstract

Several vasopressin analogues were tested on pig kidney membranes for their ability to activate adenylate cyclase and to inhibit the binding of [8-lysine]vasopressin. Both the adenylate cyclase activation and hormonal binding were measured on the same enzyme preparation and under identical were measured on the same enzyme preparation and under identical experimental conditions. A preincubation period in the presence of hormone allowed the binding process to reach equilibrium. Peptide concentrations causing half-maximal adenylate cyclase activation (apparent Km) were, in the order of decreasing affinity:2.5 to 7.0 to 7.0 times 10-10 M [8-lysine] vasopressin, 3.1 to 4.0 times 10-9 M [8-arginine] vasopressin, 2.0 to 3.0 times 10-9 M [I,6-alpha-deaminocystathionine, 8-ornithine]vasopressin, 3.1 times 10-7 M des-9-glycineamide[8-lysine]vasopressin, 0.5 to 1.0 times 10-6 M[1,6-alpha-deaminocystathionine, 2-0-tert...