Abstract
Newly-hatched chicks were fed a diet with (control group) or without (deficient group) vitamin A, by pair-feeding based on the deficient group, for 26 days. During the feeding, the activities of phosphoribosyl pyrophosphate amidotransferase [EC 2.4.2.14] involved in purine nucleotide de novo synthesis, glutamine synthetase [EC 6.3.1.2] which functions to form glutamine from glutamate and NH_3, and of five enzymes (5'-nucleotidase [EC 3.1.3.5], purine nucleoside phosphorylase [EC 2.4.2.1], adenosine deaminase [EC 3.5.4.4], guanine deaminase [EC 3.5.4.3], and xanthine dehydrogenase [EC 1.2. 1.37]) involved in purine nucleotide catabolic pathways in the liver were assayed in each group at the several stages of vitamin A deficiency, and also uric acid concentrations in blood were determined. The results obtained showed that, at an early stage of vitamin A deficiency, the activities of all enzymes assayed in the deficient group were markedly in-creased compared with those of the pair-fed control group. Similarly, an increase of uric acid in blood of chicks with vitamin A deficiency was observed. These results suggest that vitamin A might be involved in the regulation of protein metabolism in chicks.
