title: Adenylate kinase-catalyzed phosphoryl transfer couples ATP utilization with its generation by glycolysis in intact muscle.
abstract: We previously suggested that an importance of adenylate kinase (AdK) in skeletal muscle is to function as a high energy phosphoryl transfer system regulating ATP generation in correspondence with its consumption by specific cellular processes. The present experiments are intended to define the ATP-generating system coupled to and regulated by AdK-catalyzed phosphotransfer in skeletal muscle and also to examine the relationship between AdK- and creatine kinase (CK)-catalyzed phosphotransfer. Rates of phosphoryl transfer catalyzed by AdK were assessed in intact, isolated rat diaphragm by determining rates of AMP phosphorylation with endogenously generated [gamma-18O]ATP under conditions of altered anaerobic and aerobic ATP production. AdK-catalyzed phosphoryl transfer rates accelerated incrementally up to 12-fold in direct proportion to stimulated contractile frequency in parallel with equivalent increases in rates of ATP generation by lactate producing glycolysis. Stoichiometric equivalent increases of AdK-catalyzed phosphotransfer and anaerobic ATP production also occurred up to more than 20-fold when oxidative phosphorylation was impaired by either O2 deprivation or treatment with KCN or p-(trifluoromethoxy)-phenylhydrazone. These enhanced rates of AMP phosphorylation were balanced by virtually identically increased rates of AdK-catalyzed generation of AMP. This AMP was traced to arise from AdK-catalyzed phosphotransfer involving ADP generated by a muscle ATPase. Increased AdK-catalyzed phosphotransfer paired with the apparent compensatory increase in ATP generation by anaerobic glycolysis in oxygen-deprived muscle occurred coincident with diminished rates of CK-catalyzed phosphoryl transfer indicative of a pairing between oxidatively produced ATP and CK-catalyzed phosphotransfer. A metabolic model consistent with these results and conforming to the Mitchell general principle of vectorial ligand conduction is suggested.
authors.affiliation: Department of Biochemistry, University of Minnesota, Medical School, Minneapolis 55455, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Zeleznikar
authors.forename: P P
authors.initials: PP
authors.lastname: Dzeja
authors.forename: N D
authors.initials: ND
authors.lastname: Goldberg
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000249:Adenosine Monophosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000263:Adenylate Kinase / Q000378:metabolism*; D000693:Anaerobiosis; D000818:Animals; D003402:Creatine Kinase / Q000378:metabolism*; D003964:Diaphragm / Q000378:metabolism; D006019:Glycolysis; D066298:In Vitro Techniques; D007700:Kinetics; D007773:Lactates / Q000032:analysis; D008297:Male; D008954:Models, Biological; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology; D010103:Oxygen Isotopes; D010770:Phosphotransferases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D007773:Lactates; D010103:Oxygen Isotopes; D000249:Adenosine Monophosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D010770:Phosphotransferases; D003402:Creatine Kinase; D000263:Adenylate Kinase