The biosynthesis of N-phosphorylcreatine: an investigation of the postulated alternative pathway

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Abstract
The reaction; 3-phosphoglycerate + N-phosphorylcreatine 1,3-diphosphoglycerate + creatine, does not involve a direct . phosphoryl-group transfer catalysed by a single enzyme. The overall reaction in both directions is catalyzed by preparations from rat and rabbit skeletal muscle in the presence of either oxidized or reduced diphosphopyridine nucleotide. The pyridine nucleotides function by virtue of their non-enzymic conversion into, or as a result of their contamination by, adenosine diphosphate ribose, which undergoes enzymic hydrolysis to adenosine 5[image]-phosphate. Skeletal-muscle preparations, treated with charcoal to remove adenine di- and tri-phosphate, catalyzed the conversion of highly purified samples of adenosine 5[image]-phosphate into adenosine triphosphate in the presence of either N-phosphorylcreatine or phosphoenolpyruvate. Adenosine triphosphate is also formed when adenosine 5[image]-phosphate and N-phosphorylcreatine are incubated with myokinase and creatine phosphoryltransferase. Rabbit skeletal muscle contains an enzyme which hydrolyzes adenosine diphosphate ribose to adenosine 5[image]-phosphate, but which does not hydrolyze either oxidized or reduced diphosphopyridine nucleotide.