Specificity of Creatine Phosphokinase

Abstract

SOME of the properties of the enzyme creatine phosphokinase have recently been described¹; but no experiments were reported on the activity of the enzyme with substrates other than adenosine tri-phosphate, adenosine diphosphate, phosphocreatine and creatine. Such experiments are in progress and will be reported in due course. A recent publication by Armstrong², in which it was shown that the administration of N-ethylglycocyamine (negmine) was followed by the urinary excretion of N-ethyl-glycocyamidine (negmidine), suggested that a phosphorylation reaction may have been involved. It was therefore of interest to determine whether negmine could be phosphorylated by the creatine phosphokinase system.