期刊
ASTROBIOLOGY
卷 9, 期 5, 页码 483-490出版社
MARY ANN LIEBERT, INC
DOI: 10.1089/ast.2008.0280
关键词
Amino acid synthesis; Meteorites; Hydrothermal vents; Genetic code; Protein evolution; Thermodynamics
资金
- Canada Research Chairs
- Natural Sciences and Engineering Research Council of Canada
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.
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