The purification of formiminotransferase and cyclodeaminase by combination of affinity chromatography and isoelectric focusing

The twin enzyme glutamate-formiminotransferase and formiminotetrahydrofolate-cyclodeaminase were purified by subsequent ammonium sulphate fractionation, affinity chromatography with tetrahydrofolate covalently bound to Sepharose 4B and following isoelectric focusing. In the presence of formiminoglutamate the major part of the enzyme focused at pH 5.8 and was electrophoretically homogeneous. Another peak with the enzyme activity focusing at pH 4.5 was found in low amount but it was a heterogeneous protein mixture. The presence of formiminoglutamate in the course of affinity chromatography appeared to be necessary for achieving the purified enzyme.