プリンの分解と動物進化 : 尿酸分解酵素群の細胞内存在様式と性質

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The end product of purine metabolism varies from species to species. In man and other primates and birds, the end product is uric acid because they do not possess uricase (EC 1.7.3.3) activity. In mammals other than primates and some reptiles, the end product is allantoin ; uricase is responsible for the hydrolysis of uric acid to allantoin. In most fish and amphibia, the allantoin formed is further degraded to urea and glyoxylate via allantoic acid by allantoinase (EC 3.5.2.5) and allantoicase (EC 3.5.3.4). In some marine invertabrates and crustaceans the urea formed is hydrolysed to NH_3 and CO_2 by urease (EC 3.5.1.5). Because the degradation of purines is much less complete in higher animals, it is apparent that certain enzymes have been lost during animal evolution, e.g. uricase, allantoinase, allantoicase, and urease. In the present study, subcellular localization and properties of enzymes involved in purine degradation were examined with 5 amphibian and 13 fish liver. 1. Allantoinase and allantoicase were co-purified from frog (Rana catesbeiana) liver to homogeneity. The ratio of the two enzyme activities remained constant during purification and was unchanged by a variety of treatments of the purified enzyme. These results suggest that allantoinase and allantoicase are located in the same protein (allantoinase and allantoicase complex). It was found that the two hepatic enzyme activities were also associated with the same protein in other frog (Xenopus laevis and Rana nigromaculata), tadpoles (Rana catesbeiana), and newts (Triturus pyrrhogaster). In contrast, allantoinase and allantoicase were found to be different proteins in marine fish and invertebrate liver. Allantoinase and allantoicase complex was designated ALNC, allantoinase ALN and allantoicase ALC. 2. Uricase was located in the peroxisomal matrix of amphibian liver. 3. ALNC of Rana catesbeiana was suggested to be located at the cytoplasmic side of the intracellular granule membrane. 4. The ALNC-binding protein was suggested to be present in the intracellular granule membrane. 5. Uricase was located in the peroxisomal matrix in fish liver. 6. Subcellular localization of hepatic ALN and ALC was found to vary among fishes as follows. Type 1. ALN was located both in the peroxisomal matrix and in the cytosol and ALC in the peroxisomal matrix (sardine, young yellow-tail, flying fish, yellow mackerel and bonito). Type 2. ALN was located both in the peroxisomal matrix and in the cytosol, and ALC at the external face of the peroxisomal membrane (mackerel and grunt). Type 3. ALN was located in the cytosol and ALC at the external surface of the peroxisomal membrane (crucian carp, large mouth bass and sunfish). Type 4. ALN was located in the cytosol and ALC in the peroxisomal matrix (carp, gray mullet and pale chab).
九州歯科学会の論文
1984-04-25

プリンの分解と動物進化 : 尿酸分解酵素群の細胞内存在様式と性質

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