Prebiotic Chemistry that Could Not Not Have Happened
Prebiotic Chemistry that Could Not Not Have Happened
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DOI：
10.3390/life9040084
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发表时间：
2019-12-01
期刊：
影响因子：
3.2
通讯作者：
Biondi, Elisa
中科院分区：
文献类型：
--
作者：
Benner, Steven A.;Kim, Hyo-Joong;Biondi, Elisa
我们提出了一条直接途径，RNA可能在冥古宙从铁矾石-磁铁矿地幔、火山SO2气体以及在冥古宙大气中产生大量HCHO和催化量乙醇醛的公认过程中出现。在化学中，这是不可能不发生的，这些会产生稳定的亚硫酸盐添加产物，这些产物一定会像雨一样落在表面，在那里它们不可避免地会缓慢释放出产生更高碳水化合物的活性物质。高碳水化合物的形成受到亚硫酸盐形成的自我限制，而硼酸盐矿物可能控制了发生在任何半干旱表面上的醛醇反应，以捕获沉淀。所有这些过程都有经过充分研究的实验室关联。此外，任何有磷酸盐的半干旱土地都应该有磷酸酐，磷酸酐与NH3一起产生碳水化合物衍生物，直接与核碱基反应形成典型核苷。这些被硼磷酸镁矿物（例如，褐铁矿）和/或三偏磷酸硼酸盐在Ni2+催化下磷酸化，得到核苷5 '-二磷酸，通过多种机制寡聚成RNA。在这个路径假说中，形成核碱基所需的减少的前体来自一个或多个中等大小(10（23)-10（20）公斤）的撞击体，这些撞击几乎肯定是在月球形成事件之后到达的。它们的铁金属含量几乎肯定在冥古宙大气中产生了氨、核碱基前体和其他还原物，因为它暂时使大气与地幔失去了氧化还原平衡。如果冥古宙的地球上有半干旱的土地，那么除了这条路径上的步骤是不可避免的，这些过程也可能发生在火星上。改编自通讯作者于2019年10月12日在莫斯科罗蒙诺索夫国立大学举行的全俄科学节上的演讲，是约翰·邓普顿基金会和美国宇航局天体生物学计划支持的一个为期三年的项目的成果。献给大卫·迪默，在他80岁生日之际。
We present a direct route by which RNA might have emerged in the Hadean from a fayalite-magnetite mantle, volcanic SO2 gas, and well-accepted processes that must have created substantial amounts of HCHO and catalytic amounts of glycolaldehyde in the Hadean atmosphere. In chemistry that could not not have happened, these would have generated stable bisulfite addition products that must have rained to the surface, where they unavoidably would have slowly released reactive species that generated higher carbohydrates. The formation of higher carbohydrates is self-limited by bisulfite formation, while borate minerals may have controlled aldol reactions that occurred on any semi-arid surface to capture that precipitation. All of these processes have well-studied laboratory correlates. Further, any semi-arid land with phosphate should have had phosphate anhydrides that, with NH3, gave carbohydrate derivatives that directly react with nucleobases to form the canonical nucleosides. These are phosphorylated by magnesium borophosphate minerals (e.g., luneburgite) and/or trimetaphosphate-borate with Ni2+ catalysis to give nucleoside 5 '-diphosphates, which oligomerize to RNA via a variety of mechanisms. The reduced precursors that are required to form the nucleobases came, in this path-hypothesis, from one or more mid-sized (10(23)-10(20) kg) impactors that almost certainly arrived after the Moon-forming event. Their iron metal content almost certainly generated ammonia, nucleobase precursors, and other reduced species in the Hadean atmosphere after it transiently placed the atmosphere out of redox equilibrium with the mantle. In addition to the inevitability of steps in this path-hypothesis on a Hadean Earth if it had semi-arid land, these processes may also have occurred on Mars. Adapted from a lecture by the Corresponding Author at the All-Russia Science Festival at the Lomonosov Moscow State University on 12 October 2019, and is an outcome of a three year project supported by the John Templeton Foundation and the NASA Astrobiology program. Dedicated to David Deamer, on the occasion of his 80th Birthday.