Integration of ion exchange and ultrafiltration steps studied during purification of formate dehydrogenase using DEAE dextran

Summary Purification of formate dehydrogenase based on ionic properties combined with ultrafiltration is described. The enzyme was allowed to bind to high molecular weight DEAE dextran at low ionic strength forming a complex of high molecular weight retained behind an ultrafiltration membrane with a cut-off range of 300 000 dalton. When the ionic strength was increased, the enzyme dissociated from the DEAE dextran and could be recovered in the filtrate.