[High-voltage electrophoresis of dihydrofolate reductase from Escherichia coli W 3110 (author's transl)].

A method for the high-voltage electrophoresis of dihydrofolate reductase from Escherichia coli W 3110 is described. Dihydrofolate reductase catalyses the reduction of dihydrofolic acid to tetrahydrofolic acid. By addition of a tetrazolium salt, tetrahydrofolic acid reacts by formation of a violet water insoluble formazane which is an indicator for the enzyme. Besides several unspecific bands, two isoenzymes of the dihydrofolate reductase from Escherichia coli W 3110 are found which are specificially inhibited by the folate antagonists methotrexate and trimethoprime in a concentration of 0, 1muM, 1 muM respectively.