核苷酸分解代谢
中文名称
通路描述
嘌呤碱基鸟嘌呤和次黄嘌呤 (由腺嘌呤通过嘌呤 salvage 途径事件衍生而来) 被转化为黄嘌呤，然后转化为尿酸，并从体内排出 (Watts 1974)。该途径在人类和灵长类动物中的终点是不寻常的。大多数其他哺乳动物进一步代谢尿酸以产生更可溶性终产物，关于高尿酸水平在正常人类生理中可能发挥的作用的推测很多。在三个反应的平行序列中，嘧啶碱基胸腺嘧啶和尿嘧啶分别被转化为 beta-氨基异丁酸和 beta-亚氨酸。这两种分子均出现在人类尿液中，似乎是嘧啶分解代谢的正常终产物 (Griffith 1986)。然而，线粒体 AGXT2 也可催化这两种分子的转氨作用，与丙酮酸结合，产生 2-酮酸，可进一步通过支链氨基酸和短链脂肪酸分解代谢反应代谢 (Tamaki et al. 2000)。NUDT 和 NTPD 家族成员催化核苷酸中磷酸键的水解也被归类在此，尽管这些分解代谢反应的生理作用各不相同。
英文描述
Nucleotide catabolism The purine bases guanine and hypoxanthine (derived from adenine by events in the purine salvage pathways) are converted to xanthine and then to uric acid, which is excreted from the body (Watts 1974). The end-point of this pathway in humans and hominoid primates is unusual. Most other mammals metabolize uric acid further to yield more soluble end products, and much speculation has centered on possible roles for high uric acid levels in normal human physiology.In parallel sequences of three reactions each, the pyrimidines thymine and uracil are converted to beta-aminoisobutyrate and beta-alanine respectively. Both of these molecules are excreted in human urine and appear to be normal end products of pyrimidine catabolism (Griffith 1986). Mitochondrial AGXT2, however, can also catalyze the transamination of both molecules with pyruvate, yielding 2-oxoacids that can be metabolized further by reactions of branched-chain amino acid and short-chain fatty acid catabolism (Tamaki et al. 2000).Hydrolysis of phosphate bonds in nucleotides catalyzed by members of the NUDT and NTPD families of enzymes have been grouped here as well, although the physiological roles of these groups of catabolic reactions are diverse.
所含基因
1 个基因