Regulation of xanthine dehydrogenase and purine nucleoside phosphorylase levels in chick liver.

Abstract

A number of agents which have been shown to affect the levels of xanthine dehydrogenase (XDH) and purine nucleoside phosphorylase (PNP) (EC 2.4.2.1) in the liver of the chick are listed in Table I. We have divided these agents into four groups depending upon which enzymes are affected coordinately. Group A agents induce increases in the levels of XDH, PNP and probably other enzymes involved in purine synthesis. So far Group B agents appear to specifically act on XDH, although studies of other enzymes may reveal additional effects. Group C contains representative steroid hormones which induce or suppress levels of XDH and in one case (hydrocortisone) induces an increase in tyrosine transaminase. Group D contains unsaturated fatty acids including oleic, linoleic and linolenic acids. These agents suppress levels of XDH and PNP.