The creatine phosphokinase activity of serum is determined by a procedure in which
adenosine triphosphate, liberated by the action of the enzyme, is linked to the reduction of
nicotinamide-adenine dinucleotide phosphate and the formation of reduced nicotinamide-
adenine dinucleotide phosphate followed spectrophotometrically. The enzyme substrate for
the reaction is prepared in bulk, freeze-dried, and distributed in gelatinecovered capsules.
The capsule contents are reconstituted immediately before use by the addition of distilled …