Purification and immunochemical analysis of lactate dehydrogenase (LDH) isozymes of grass carp ( Ctenopharyngodon idella)

By chromatography and other techniques, LDH-A 4, LDH-B 4 and LDH-C 4 were purified from the white skeletal muscle, heart and liver tissues of grass carp ( Ctenopharyngodon idella), respectively. Their corresponding antibodies were prepared from rabbits immunized with purified LDH isozymes. The LDH composition and immunochemical properties were determined by using a combination of immunoprecipitation with starch gel electrophoresis. The LDH isozymes of grass carp are encoded by three gene loci: Ldh-A, Ldh-B and Ldh-C. The physicochemical properties of LDH isozymes were analyzed, including the molecular weight, amino acid composition, Km and substrate concentration, pH and temperature optima, and inhibitor concentration for denaturation. The immunochemical specificity with other freshwater fish demonstrated that the antibodies against grass carp LDH isozymes have no species specificity. Therefore, they could be applied in the identification of the subunit composition of LDH isozyme of other fish species.