The theory of diazymes and functional coupling of pyruvate kinase and creatine kinase.
The physical-chemical principles governing the interactions of enzymes having common metabolic products are presented. Methods for comparing the dissociation rates of the metabolic product and the rates of enzyme-enzyme interaction are given. Using muscle pyruvate kinase (PK) and creatine kinase (CK) as an example, it is shown that the probability of forming an enzyme-product-enzyme complex is much greater than the rate of ATP dissociation from either enzyme. Experimental evidence using 31P-NMR demonstrates that in the presence of both pyruvate kinase and creatine kinase, there is exchange of phosphate between phosphocreatine and phosphoenolpyruvate without a change in the intermediate, ATP. This confirms the formation of a PK.ATP.CK complex in an aqueous solution without enzyme attachment to a substructure. Enzymes capable of forming these mobile clusters are defined as diazymes, and the criteria for their formation are given. The metabolic implications of diazymes are discussed.
Dillon
P F
PF
Department of Physiology, Michigan State University, East Lansing 48824.
Clark
J F
JF
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D003402:Creatine Kinase / Q000378:metabolism*; D007700:Kinetics; D008956:Models, Chemical; D009097:Multienzyme Complexes / Q000378:metabolism*; D011770:Pyruvate Kinase / Q000378:metabolism*; D012995:Solubility
D009097:Multienzyme Complexes; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D011770:Pyruvate Kinase; D003402:Creatine Kinase