权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Lost organization of purine degrading enzymes in peroxisomes during animal evolution

动物进化过程中过氧化物酶体中嘌呤降解酶的组织丢失

基本信息

批准号：
10680620
负责人：
NOGUCHI Tmoo
金额：
$ 2.18万
依托单位：
Kyushu Dental College
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

End products of purine degradation very from species to species. The end product of purine degradation is urate in humans, hominoid primates and new world monkeys, allantoin by uricase in mammals other than primates and old world monkeys, allantoate by allantoinase in some teleosts, urea by allantoicase in fish and amphibians and ammonia by urease in many invertebrates.The degradation of purines to urate is common to all animal species, while the degradation of urate is much less complete in higher animals. We have reported that in marine fish, the degrading enzymes of purines to urate are located in the cytosol, while the degrading enzymes of urate to urea are located in the peroxisomes. This shows that in purine degradation, peroxisomal enzymes have been lost during evolution. Allantoinas (ALN) and allantoicase (ALC) are different protein in fish liver, whereas the two enzymes form a complex in amphibian liver.We examined how the mechanism to form amphibian allantoinase-allantoicase … More complex (ALNC) is lost in higher animals during animal evolution.(1) The cDNA encoding allantoinase of the subunit of amphibian ALNC was sequenced. We got some clones from λat 11 library using anti allantoinase of bullfrog. (2) In saltwater fish liver, the end products of purine degradation were urea and glyoxylate. Glyoxylate may be converted to glycine by alanine : glyoxylate aminotransferase for the reutilization of purine carbons. (3) It is generally accepted that all of the allantoin-degrading enzymes were lost during mammalian evolution. Suprisingly, ureidoglycollate lyase has been found in a mammalian tissue. The apparent Km (17 mM) of the rat enzyme for ureidoglycollate was much higher than that (0.33 mM) of fish-liver ureidoglycollate lyase. Mammals have lost the function in vivo by elevating the Km for ureidoglycollate during evolution. (4) We found free ALN only with ALN activity which is differ from ALN subunit composed of ALNC. The enzyme shows the middle type of fish ALN and amphibian ALNC. (5) ALN and ALC were purified from the each liver of sardine (salt water), mullet (brackish water) and crucian carp (fresh water). Amino acid sequences were determined from the part of purified ALN and ALC by protein sequencer. The cDNA of each fish was synthesied with RT-PCR using mRNA and determined full-length by DNA sequencer. In defferent habitat, DNA sequence of each fish ALN and ALC signal of transference to and destribution in peroxisomes. We compared with subunit of fish ALN and amphibian ALNC. Less

嘌呤降解的最终产物在不同物种间有很大差异。嘌呤降解的最终产物在人类、类人猿灵长类和新大陆猴中是尿酸盐，在除灵长类和旧大陆猴之外的哺乳动物中是通过尿酸酶的尿囊素，在一些硬骨鱼中是通过尿囊素酶的尿囊酸，在鱼类和两栖动物中是通过尿囊素酶的尿素，在许多无脊椎动物中是通过尿素酶的氨。嘌呤降解为尿酸盐是所有动物物种所共有的，而尿酸盐在高等动物中的降解要不完全得多。我们报道过，在海鱼中，嘌呤降解为尿酸盐的酶位于细胞质中，而尿酸盐降解为尿素的酶位于过氧化物酶体中。这表明在嘌呤降解过程中，过氧化物酶体酶在进化过程中已经丢失。尿囊素（Allantoinas，ALN）和尿囊酸酶（allantoicase，ALC）是鱼肝中的两种不同的蛋白质，而在两栖动物肝中这两种酶形成复合物 ...更多信息在动物进化过程中，ALNC复合体在高等动物中丢失。(1)对两栖类ALNC亚基尿囊素酶的cDNA序列进行了测定。用牛蛙尿囊素酶的抗血清从λat 11文库中筛选到了一些克隆。(2)在咸水鱼肝中，嘌呤降解的最终产物是尿素和乙醛酸。乙醛酸可以通过丙氨酸：乙醛酸氨基转移酶转化为甘氨酸，用于嘌呤碳的再利用。(3)人们普遍认为，所有的尿囊素降解酶在哺乳动物进化过程中丢失。令人惊讶的是，脲基乙醇酸裂解酶已在哺乳动物组织中发现。对脲基乙醇酸的大鼠酶的表观Km（17 mM）远高于鱼肝脲基乙醇酸裂解酶的表观Km（0.33 mM）。哺乳动物在进化过程中通过提高脲基乙醇酸的Km而丧失了体内的功能。(4)我们发现游离ALN仅具有ALN活性，与ALNC所组成的ALN亚基不同。该酶表现为鱼类ALN和两栖类ALNC的中间型。(5)从沙丁鱼（盐水）、鲻鱼（微咸水）和鲫鱼（淡水）的肝脏中分别纯化ALN和ALC。用蛋白质测序仪对纯化的部分ALN和ALC进行氨基酸序列测定。用RT-PCR方法合成每条鱼的cDNA，并通过DNA测序仪测定全长。在不同生境中，各鱼ALN和ALC的DNA序列在过氧化物酶体中传递和识别信号。并与鱼类ALN和两栖类ALNC的亚基进行了比较。少