Creatine kinase activity in serum and uric acid solution

Skeletal muscle creatine kinases from man and rabbit, activated to measured specific activities by thiol agents, were inactivated in human serum and in uric acid solution, and the extent of their subsequent reactivation by dithiothreitol was determined. Both enzymes were completely reactivated from uric acid solution but were only 60-70% reactivated from serum. No inactivation occurred within 14 days if serum samples contained dithiothreitol (0.01 M) and were stored at -17 degrees C.