Nippon Medical School
We have studied XDHs for more than 50 years, their main distribution and physiological significance, and their molecular properties. Initially, we investigated the reaction and regulation of urate formation in chickens, which are urate-excreting animals. For birds, the metabolic significance of removing amino acid amino groups and their purine metabolism was imagined. Studies on the inducibility of the enzyme by the protein content of the diet have confirmed that it is the metabolism of amino nitrogen. However, even in the same bird species, the distribution of XDH differed between chickens and pigeons. The XDH molecules were similar in terms of the presence of a sulfur atom in their active center, but they did not convert from XDH to XO. The Mo-S sulfur atom required for activity was essential and varied in content. However, the RC bacterium XDH is Mo-S stable. It was also found that the effect of XDH inhibitors was not inhibitory, except for allopurinol, and this was due to differences in the dynamic structure of the active site protein. The biological significance of the above is summarized. Finally, the biological relevance of only mammals changing from XDH to XO is discussed.