ENZYMES with the same catalytic function but different molecular form are called isozymes. They can be distinguished by electrophoresis, chromatography, immunochemistry, salt fractionation, or by ultracentrifugation. Electrophoresis is most commonly used in clinical laboratories.
Recently, the isozymes of lactic dehydrogenase have been studied in various neuromuscular disorders.1-8 Because creatine phosphokinase (CPK) activity is very low in tissues other than brain and muscle, study of this enzyme might be more specific for muscle disease. Serum CPK assays are used for the diagnosis of neuromuscular disorders and for the detection of the carrier state in Duchenne dystrophy.9-14
Three isozymes of CPK in various organs have been demonstrated by several investigators.15-17 No characteristic abnormality of CPK isozymes in muscle was found in progressive muscular dystrophy or other neuromuscular disorders.15-17 Several attempts have been made to examine the role of CPK activity in the initiation of contractile activity in
Goto I, Nagamine M, Katsuki S. Creatine Phosphokinase: Human Fetus and Patients. Arch Neurol. 1969;20(4):422–429. doi:10.1001/archneur.1969.00480100098014
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