title: Guanine nucleotides protect adenylate cyclase against inhibition by Pb2+.
abstract: The inhibition of rat liver adenylate cyclase (ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1) by Pb2+ could be separated into an irreversible and a reversible component. Evidence was obtained that both types of inhibition were due to free Pb2+, rather than Pb/ATP, and that Pb2+ did not act via the site wherein Mg2+ and Mn2+ activate the cyclase. Guanine nucleotides strongly counteracted the reversible inhibition of cyclase by Pb2+, providing another example of guanine nucleotide effects on adenylate cyclase function. It is suggested that the Pb2+-inhibited cyclase may be of value in the study of guanine nucleotide-cyclase interactions.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D004789:Enzyme Activation; D006150:Guanine Nucleotides / Q000494:pharmacology*; D006153:Guanosine Diphosphate / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000494:pharmacology; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D007854:Lead / Q000494:pharmacology*; D008099:Liver / Q000201:enzymology; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D051381:Rats
chemical_list: D000067956:Adenylyl Cyclase Inhibitors; D006150:Guanine Nucleotides; D006153:Guanosine Diphosphate; D007854:Lead; D006165:Guanylyl Imidodiphosphate; D008345:Manganese; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D000262:Adenylyl Cyclases; D008274:Magnesium