Adenosine- and inosine-nucleotides in the phosphorus metabolism of muscle

Abstract

The prep. of inosine-triphosphate (ITP) is described. The rates at which P04 is liberated from inosine-triphosphate and adenosinetriphosphate by myosin solns. are compared. Inosine-triphosphate was split approx. 3 times as fast as ATP. The isolation of the hitherto unknown inosine-diphosphate (IDP) is described. Phosphagen formation proceeded 5-8 times as fast in the presence of adenosine-nucleotides as in the presence of the inosine-compounds. No evidence of transfer of P from ITP to hexosemono-phosphate was obtained. The dephosphorylation of ITP in muscle extracts stops at the IDP stage. Myokinase is evidently strictly specific for adenosine-diphosphate. The phosphorylation of glucose by yeast hexokinase proceeded approx. 5 times as fast in the presence of adenosinetriphosphate as in the presence of ITP.