Comparison of Adaptations to Diet of Enzymes Involved in Uric Acid Production from IMP in Chickens and Rats

Abstract

Comparative studies were made on the effect of diets of various protein contents on the activities of the three enzymes involved in uric acid production from IMP. In chicken liver and kidney, the specific activities of cytosol 5′-nucleotidase [EC 3.1.3.5], purine nucleoside phosphorylase [EC 2.4.2.1], and xanthine dehydrogenase [EC 1.2.1.37] increased when the casein content of the diet was increased. Of the three, the activity of xanthine dehydrogenase in the liver changed most, increasing 13-fold when the dietary casein content was increased from 5 to 75%. The specific activities of cytosol 5′-nucleotidase and purine nucleoside phosphorylase only increased 2 to 3-fold after this dietary change. The responses of these enzyme activities to change in dietary protein content were less in the kidney than in the liver. In rat liver, cytosol 5′-nucleotidase and purine nucleoside phosphorylase activities did not change on administration of a high protein diet, but xanthine dehydrogenase activity decreased during adaptation to a low protein diet.