Abstract
Xanthine oxidoreductase preparations were obtained from liver of: fish Cyprinus carpio /ammonotelic/, snake Natrix natrix and chicken Gallus gallus /both uricotelic/, toad Bufo viridis and Wistar rat /both ureotelic/. The course of hypoxanthine → xanthine → → uric acid hydroxylation catalyzed by NAD+ - dependent xanthine oxidoreductases was found to be specific for each species, and especially different in case of the uricotelic ones. Substrate competition between xanthine and hypoxanthine for the enzyme active centers seems to occur for xanthine oxidoreductases from ammono- and ureotelic species, but not from the uricotelic ones.
The enzyme from fish, snake, toad and chicken liver was inhibited by NADH at micromolar concentrations and that from rat liver - by NADH at nanomolar concentrations; this suggests that in vivo the activity of only rat enzyme could be dependent on changes in the NAD+/NADH ratio in cell. Therefore, only in mammals the inhibition of xanthine oxidoreductase by NADH may spare hypoxanthine for the salvage pathway of purine nucleotide biosynthesis.
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Jezewaka, M., Kamiński, Z. & Zakrzewska, B. 66 MAMMALIAN XANTHINE OXIDOREDUCTASE - A UNIQUE ENZYME AMONG HYPOXANTHINE-HYDROXYLATING ENZYMES IN VERTEBRATES. Pediatr Res 24, 122 (1988). https://doi.org/10.1203/00006450-198807000-00090
Issue Date:
DOI: https://doi.org/10.1203/00006450-198807000-00090