PURIFICATION AND CHARACTERIZATION OF D-BETA-HYDROXYBUTYRATE DEHYDROGENASE EXPRESSED IN ESCHERICHIA-COLI

D-beta-Hydroxybutyrate dehydrogenase (BDH), a lipid-requiring enzyme, has been cloned into pUC18, expressed in Escherichia coli, and purifie d to homogeneity. The apoenzyme, i.e., the enzyme devoid of phospholip id, has no activity, but can be activated by phospholipid to a specifi c activity of 129 mu mol/(min mg). The functional properties of the en zyme expressed in E. coil were compared with the enzyme purified from rat liver. The specific activities, kinetic parameters, and phospholip id activation profiles were virtually identical. These results indicat e that the expression of the enzyme in E. coli is a viable method for producing active functional BDH and should allow for the production of specifically altered BDH molecules.