title: Creatine phosphate inhibition of adenylate deaminase is mainly due to pyrophosphate.
abstract: Inhibition of rat skeletal muscle adenylate deaminase by creatine phosphate reported previously is due to inorganic pyrophosphate present as a contaminant in commercial preparations of creatine phosphate. This conclusion is based on the following evidence: a compound that inhibits adenylate deaminase can be separated from commercially prepared creatine phosphate by ion exchange chromatography; the inhibition by "creatine phosphate" and by the separated inhibitory compound is relieved by treatment with inorganic pyrophosphatase; inhibition by inorganic pyrophosphate is similar to that produced by unpurified creatine phosphate; and pyrophosphate is present in commercially available creatine phosphate in amounts sufficient to account for the inhibition. Some commercial preparations of creatine phosphate contain much less pyrophosphate than others; these preparations are only weakly inhibitory. Inorganic triphosphate is a more powerful inhibitor of the enzyme than pyrophosphate; it may also be present as a contaminant in creatine phosphate.
mesh_terms: D000659:AMP Deaminase / Q000037:antagonists & inhibitors*; D000818:Animals; D011756:Diphosphates / Q000494:pharmacology*; D007700:Kinetics; D009132:Muscles / Q000201:enzymology; D009709:Nucleotide Deaminases / Q000037:antagonists & inhibitors*; D010725:Phosphocreatine / Q000494:pharmacology*; D051381:Rats
chemical_list: D011756:Diphosphates; D010725:Phosphocreatine; D009709:Nucleotide Deaminases; D000659:AMP Deaminase