The determination of hydroxyproline in tissue and protein samples containing small proportions of this imino acid

CREATINE KINASE IN MUSCLE OF NORMAL AND DYSTROPHIC MICE OF STRAIN 129

Hind leg muscle of normal and dystrophic mice of strain 129 was taken for individual analyses of creatine phosphokinase, total nitrogen, and collagen nitrogen. Young mice (18 to 25 days old) from one colony and adult mice (6 weeks to 3 months old) from another colony were used. The enzyme was assayed by measuring the formation of creatine from added creatine phosphate and adenosine diphosphate. Sulphydryl compounds were found to cause a large increase in activity. The enzyme activity was based on non-collagen nitrogen. The values in dystrophic mice were lower than in unaffected littermates, whether young or old, but the difference was significant only in young mice. The total nitrogen content was significantly lower than normal in all dystrophic mice, but there was no difference between dystrophics and normals in collagen nitrogen.