ショウジョウバエにおけるプリン代謝の遺伝生化学的研究〔英文〕

概要

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An eye color mutant of Drosophila melanogaster, ry, contains no uric acid at any developmental stage, but accumulates a large amount of hypoxanthine compared with the amount of xanthine at pupal and imaginal stages.An enzyme concerned with uric acid production in D. melanogaster of the wild type is a xanthine dehydrogenase, which has both the activities of xanthine oxidation and DPNH oxidation. The xanthine dehydrogenase from ry mutant, however, does not have xanthine oxidative activity, but retains the activity of DPNH oxidation. The enzymatic activity of DPNH oxidation in ry is at the same level as in the wild strain. The xanthine oxidative activity in the enzyme from heterozygous strain, ry/+, is one-half of the activity in the wild strain, but the DPNH oxidative activity is at the same level as in a wild strain.These results suggest that xanthine dehydrogenase produced in the ry mutant is an enzyme molecule lacking the active site of xanthine oxidation.The activity of guanase, which catalyzes the conversion of guanine to xanthine, is observed in pupal and imaginal stages of both wild and ry strains. From these results, it is shown that xanthine, which is a precursor of uric acid, is derived not only from hypoxanthine with dehydrogenase but also from guanine with guanase.