A Thermodynamic Basis for Prebiotic Amino Acid Synthesis and the Nature of the First Genetic Code
A Thermodynamic Basis for Prebiotic Amino Acid Synthesis and the Nature of the First Genetic Code
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DOI：
10.1089/ast.2008.0280
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发表时间：
2009-06-01
期刊：
影响因子：
4.2
通讯作者：
Pudritz, Ralph E.
中科院分区：
文献类型：
--
作者：
Higgs, Paul G.;Pudritz, Ralph E.
在蛋白质中使用的20种氨基酸中，有10种是在米勒的大气放电实验中形成的。另外两个被提出的益生元氨基酸合成的主要来源包括热液喷口形成和通过陨石传递到地球。我们结合了这些不同机制形成的氨基酸频率的观测和实验数据，并表明，无论来源如何，这10种早期氨基酸在益生元环境中都可以按丰度递减的顺序排列。这个顺序可以用热力学来预测。早期氨基酸的相对丰度很可能反映在遗传密码起源时第一批蛋白质的组成中。剩下的氨基酸在其生化合成途径进化后被纳入蛋白质。这与遗传密码通过逐步添加新的氨基酸而进化的理论是一致的。这些迹象表明，早期生物化学的关键方面可能是普遍的。
Of the 20 amino acids used in proteins, 10 were formed in Miller's atmospheric discharge experiments. The two other major proposed sources of prebiotic amino acid synthesis include formation in hydrothermal vents and delivery to Earth via meteorites. We combine observational and experimental data of amino acid frequencies formed by these diverse mechanisms and show that, regardless of the source, these 10 early amino acids can be ranked in order of decreasing abundance in prebiotic contexts. This order can be predicted by thermodynamics. The relative abundances of the early amino acids were most likely reflected in the composition of the first proteins at the time the genetic code originated. The remaining amino acids were incorporated into proteins after pathways for their biochemical synthesis evolved. This is consistent with theories of the evolution of the genetic code by stepwise addition of new amino acids. These are hints that key aspects of early biochemistry may be universal.