Abstract
At the focus of abiotic chemical reactions is the synthesis of ribose. No satisfactory explanation was provided as to the missing link between the prebiotic synthesis of ribose and prebiotic RNA (preRNA). Hydrogen cyanide (HCN) is assumed to have been the principal precursor in the prebiotic formation of aldopentoses in the formose reaction and in the synthesis of ribose. Ribose as the best fitting aldopentose became the exclusive sugar component of RNA. The elevated yield of ribose synthesis at higher temperatures and its protection from decomposition could have driven the polymerization of the ribose-phosphate backbone and the coupling of nucleobases to the backbone. RNA could have come into being without the involvement of nucleotide precursors. The first nucleoside monophosphate is likely to have appeared upon the hydrolysis of preRNA contributed by the presence of reactive 2′-OH moieties in the preRNA chain. As a result of phosphorylation, nucleoside monophosphates became nucleoside triphosphates, substrates for the selective synthesis of genRNA.
Highlights
Fossilized microorganisms found in hydrothermal vents could have appeared on Earth around 4.3 bya, after the formation of oceans (~4.4 bya) and Earth (4.5 bya) [1,2]
A simplified reaction pathway involving free radicals has been identified through density-functional theory (DFT) computational calculations leading to the formation of ribosyl and ribonucleosides, where catalysis by Ca2+ and CaOH+ was involved
These results suggest that Ca2+ cations may not be directly involved in the formation of ribose from glyceraldehyde [8]
Summary
Fossilized microorganisms found in hydrothermal vents could have appeared on Earth around 4.3 bya (billion years ago), after the formation of oceans (~4.4 bya) and Earth (4.5 bya) [1,2]. Water was photolyzed and generated in statu nascendi hydrogen and oxygen in the atmosphere [25] containing N2, CO, during the Hadean geologic eon of the Earth about 4.6 billion years ago before the Archean. Ammonia, and other related compounds are polar because of the tetragonal arrangement of the electrons of the central atom, including the non-bonding electron-pairs, which results in close to tetrahedral H-X-H bond angles and non-zero overall molecular dipoles. This work focuses on those reactions of abiotic synthesis of organic molecules with particular attention to ribose selected as the precursor to life [18] that made possible the formation of random–sequence non-coding RNA and further the development of genetic RNA. Those compounds and reactions deserve consideration that has already been suggested and known for their evolutionary involvement
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