Purification and comparison of sex-dependent and sex-independent gulonolactonase of rats.

In view of the androgen control exerted upon renal gulonolactonase activity in the rat and the absence of such control upon hepatic enzyme activity, the renal enzymes from the adult male and female have been compared with each other as well as with the male hepatic enzyme. The enzymes from the three sources are immunologically alike. Moreover, these enzymes have been characterized with respect to pH optimum, relative substrate specificity, Km, metal ion requirement, and isoelectric point and found to be indistinguishable. Gulonolactonase from male rat liver has been purified to near homogeneity as judged by electrofocusing and disc gel electrophoresis. The molecular weight is estimated to be 42,000 based on gel retardation chromatography and on electrophoresis on acrylamide in the presence of sodium dodecyl sulfate. The turnover number is estimated to be 13,500 moles of n-gulonolactone hydrolyzed per mole of enzyme per min.