Immunoassay of enzymes

Antisera against purified human placental alkaline phosphatase (PAP) and crystallized creatine kinase (CK) isoenzyme from human skeletal muscle (MM) were raised in rabbits. The PAP antiserum was shown by radial immunodiffusion not to react with purified alkaline phosphatases from human liver and intestine, nor with the alkaline phosphatase in sera from patients with osteoblastic bone disease. CK antiserum also demonstrated no cross-reaction and was precipitated quantitatively by its homologous antisera. A "rocket" electroimmunoassay for PAP and CK is described. The method is simple, reproducible and uses small volumes of antiserum. The isoenzyme patterns were compared with those developed by several electrophoretic methods. These techniques share with other immunoassay the advantages of specificity for the antigen and enhance the quantitation of isoenzyme assays.