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Analysis for peptide compounds in carbonaceous chondrites and experimental simulation of abiotic peptide formation

碳质球粒陨石中肽化合物的分析及非生物肽形成的实验模拟

基本信息

批准号：
11440166
负责人：
SHIMOYAMA Akira
金额：
$ 8.7万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

The Yamato-791198 and Murchison carbonaceous chondrites were analyzed for dipeptides and diketopiperazines as well as amino acids and hydantoins by gas chromatography combined with mass spectrometry. Glycylglycine (gly-gly) and cyclo (gly-gly) were detected at the concentrations of ll and 18 pmol g^<-1>, respectively, in Yamato-791198 and 4 and 23 pmol g^<-1>, respectively, in Murchison. No other dipeptide and diketopiperazine were detected. Five hydantoins were detected at 8 to 65 pmol g^<-1> in Yamato-791198 and seven in Murchison at 6 to 104 pmol g^<-1>. Total concentration of the glycine (gly) dimers is approximately four orders of magnitude less than the concentration of free gly in Yamato-791198, and three orders of magnitude less than that in Murchison. The absence of L- and LL-stereoisomers of dipeptides consisting of protein amino acids indicates that gly-gly and cyclo(gly-gly) detected are proper to the chondrites but not from terrestrial contaminants. A possibility was discussed that the gly dimers might have been formed by condensation of gly monomers but not formed through N-carboxyanhydrides of gly.We found a novel thermal polymerization of alanine, which would be likely applied to other amino acids, by taking advantage of a highly polar feature of molten urea as well as the dehydrating ability of urea. The polymer obtained by this method was revealed to have a special structure, bearing a hydantoin ring at the JV-terminal. From the viewpoint of chemical evolution, this study offered a new candidate for a dehydrating agent or a polycondensation medium that can be present on the primitive Earth.

用气相色谱-质谱法分析了Yamato-791198和Murchison碳质球粒陨石中的二肽和二酮基哌嗪，以及氨基酸和海因。甘氨酰甘氨酸(Gly-Gly)和环状甘氨酸(Gly-Gly)在Yamato-791198和Murchison中的浓度分别为11和18pmolg^~(-1)和4和23pmolg^~(-1)&gt；未检测到其他二肽和二酮哌嗪。在Yamato-791198和Murchison中，在8~65pmolg^-1&gt；中检测到5个海因，在6~104pmolg^-1&gt；中检测到7个。甘氨酸二聚体的总浓度比Yamato-791198中的游离甘氨酸浓度低约4个数量级，比Murchison中的甘氨酸浓度低3个数量级。蛋白质氨基酸组成的二肽的L和LL-立体异构体的缺失表明，所检测到的甘氨酸和环(甘氨酸-甘氨酸)是球粒陨石所特有的，而不是来自陆源污染物。讨论了甘氨酸二聚体可能是由甘氨酸单体缩合而不是通过甘氨酸的N-羧酸酐形成的可能性，我们发现了一种新的丙氨酸热聚合方法，该方法利用了熔融尿素的高极性特性以及尿素的脱水能力，很可能适用于其他氨基酸。通过这种方法得到的聚合物具有特殊的结构，在JV末端带有一个海因环。从化学进化的角度来看，这项研究为原始地球上可能存在的脱水剂或缩聚介质提供了一个新的候选者。