Hafez Rehab M, Abdel-Rahman Tahany M, Naguib Rasha M
Botany and Microbiology Department, Faculty of Science, Cairo University, Giza 12613, Egypt.
Microanalytical Center, Faculty of Science, Cairo University, Giza 12613, Egypt.
J Adv Res. 2017 Sep;8(5):475-486. doi: 10.1016/j.jare.2017.05.003. Epub 2017 May 11.
Uric acid increased accumulation and/or reduced excretion in human bodies is closely related to pathogenesis of gout and hyperuricemia. It is highly affected by the high intake of food rich in purine. Uric acid is present in both higher plants and microorganisms with species dependent concentration. Urate-degrading enzymes are found both in plants and microorganisms but the mechanisms by which plant degrade uric acid was found to be different among them. Higher plants produce various metabolites which could inhibit xanthine oxidase and xanthine oxidoreductase, so prohibit the oxidation of hypoxanthine to xanthine then to uric acid in the purine metabolism. However, microorganisms produce group of degrading enzymes uricase, allantoinase, allantoicase and urease, which catalyze the degradation of uric acid to the ammonia. In humans, researchers found that several mutations caused a pseudogenization (silencing) of the uricase gene in ancestral apes which exist as an insoluble crystalloid in peroxisomes. This is in contrast to microorganisms in which uricases are soluble and exist either in cytoplasm or peroxisomes. Moreover, many recombinant uricases with higher activity than the wild type uricases could be induced successfully in many microorganisms. The present review deals with the occurrence of uric acid in plants and other organisms specially microorganisms in addition to the mechanisms by which plant extracts, metabolites and enzymes could reduce uric acid in blood. The genetic and genes encoding for uric acid in plants and microorganisms are also presented.
人体内尿酸积累增加和/或排泄减少与痛风和高尿酸血症的发病机制密切相关。它受到高嘌呤食物摄入量的显著影响。尿酸存在于高等植物和微生物中，其浓度因物种而异。植物和微生物中都发现了尿酸降解酶，但发现植物降解尿酸的机制在它们之间有所不同。高等植物产生各种代谢产物，这些代谢产物可以抑制黄嘌呤氧化酶和黄嘌呤氧化还原酶，从而在嘌呤代谢中阻止次黄嘌呤氧化为黄嘌呤进而氧化为尿酸。然而，微生物产生一组降解酶，即尿酸酶、尿囊素酶、尿囊酸酶和脲酶，它们催化尿酸降解为氨。在人类中，研究人员发现，几种突变导致了祖先猿类中尿酸酶基因的假基因化（沉默），尿酸酶以不溶性晶体的形式存在于过氧化物酶体中。这与微生物不同，微生物中的尿酸酶是可溶的，存在于细胞质或过氧化物酶体中。此外，许多活性高于野生型尿酸酶的重组尿酸酶可以在许多微生物中成功诱导产生。本综述除了介绍植物提取物、代谢产物和酶降低血液中尿酸的机制外，还讨论了尿酸在植物和其他生物特别是微生物中的存在情况。同时还介绍了植物和微生物中尿酸的遗传学及编码基因。
