FACTORS INFLUENCING THE ELECTROPHORETIC MIGRATION OF LACTIC DEHYDROGENASE ISOZYMES.

Abstract

Abstract The determination of lactic dehydrogenase isozymes is of interest in clinical medicine and various other biochemical fields. Different electrophoretic methods or conditions, however, may produce inconsistent results. These inconsistencies were investigated by means of starch gel and dilute agar electrophoresis. It was found that, in buffers of increasing dilution, the relatively more basic isozymes, especially 5, tend to migrate toward the anode instead of the cathode. This effect appeared to be due to the migration of these isozymes in association with anionic substances when the buffer was sufficiently dilute. Anionic components involved could be either originally bound to the isozyme in the homogenate or could be present in the electrophoretic medium. The former possibility is unlikely, since re-electrophoresis of isozyme 5, purified under conditions which would separate it from anionic components, continued to show a dependence upon ionic strength. When the concentration of agar or starch gel was increased, the interactions with the isozymes were increased. When the isozymes were separated in an agar plate which had been subjected to preliminary electrophoresis before sample application, the effect of lower briffer concentration was then largely eliminated. Interactions between the isozymes and a component or components of the electrophoretic media are therefore most consistent with these results. The use of buffers of sufficiently high concentration to eliminate the interactions described may be important in avoiding incorrect interpretations of LDH isozyme patterns.