Miyakawa Shin, Yamanashi Hiroto, Kobayashi Kensei, Cleaves H James, Miller Stanley L
Department of Chemistry and Biotechnology, Faculty of Engineering, Yokohama National University, Japan.
Proc Natl Acad Sci U S A. 2002 Nov 12;99(23):14628-31. doi: 10.1073/pnas.192568299. Epub 2002 Oct 30.
Most models of the primitive atmosphere around the time life originated suggest that the atmosphere was dominated by carbon dioxide, largely based on the notion that the atmosphere was derived via volcanic outgassing, and that those gases were similar to those found in modern volcanic effluent. These models tend to downplay the possibility of a strongly reducing atmosphere, which had been thought to be important for prebiotic synthesis and thus the origin of life. However, there is no definitive geologic evidence for the oxidation state of the early atmosphere and bioorganic compounds are not efficiently synthesized from CO(2) atmospheres. In the present study, it was shown that a CO-CO(2)-N(2)-H(2)O atmosphere can give a variety of bioorganic compounds with yields comparable to those obtained from a strongly reducing atmosphere. Atmospheres containing carbon monoxide might therefore have been conducive to prebiotic synthesis and perhaps the origin of life. CO-dominant atmospheres could have existed if the production rate of CO from impacts of extraterrestrial materials were high or if the upper mantle had been more reduced than today.
大多数关于生命起源时期原始大气的模型表明，大气主要由二氧化碳主导，这主要基于大气是通过火山排气形成的这一观点，并且那些气体与现代火山流出物中的气体相似。这些模型往往淡化了强还原大气的可能性，而强还原大气曾被认为对前生物合成以及生命起源很重要。然而，对于早期大气的氧化态并没有确凿的地质证据，而且生物有机化合物也无法从二氧化碳大气中高效合成。在本研究中，结果表明一氧化碳 - 二氧化碳 - 氮气 - 水的大气能够产生多种生物有机化合物，其产量与从强还原大气中获得的产量相当。因此，含有一氧化碳的大气可能有利于前生物合成，也许还有利于生命起源。如果外星物质撞击产生一氧化碳的速率很高，或者上地幔比现在更还原，那么以一氧化碳为主导的大气就有可能存在。
