Formation of Nucleobases from Formamide in the Presence of Iron Oxides: Implication in Chemical Evolution and Origin of Life

Shanker, Uma; Bhushan, Brij; Bhattacharjee, G.; Kamaluddin, .

doi:10.1089/ast.2010.0530

Cited by 32 publications

(26 citation statements)

References 38 publications

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“…Hematite and akaganeite appear as rod shaped structures, 102.16, 85.93 nm long and 18.32, 18.07 nm thick, respectively. The occurrence of chloride peak confirms the formation of akaganeite (Shanker et al, 2011).…”

Section: Characteristics Of Iron Oxidessupporting

confidence: 53%

Photocatalytic degradation of polycyclic aromatic hydrocarbon benzo[a]pyrene by iron oxides and identification of degradation products

Gupta

2015

Chemosphere

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Section: Characteristics Of Iron Oxidessupporting

confidence: 53%

Photocatalytic degradation of polycyclic aromatic hydrocarbon benzo[a]pyrene by iron oxides and identification of degradation products

Gupta

2015

Chemosphere

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“…Some of the most successful attempts to simulate primitive abiogenic reactions have been conducted under conditions that are compatible with reconstructed conditions at the geothermal fields of the anoxic Earth. These promising experiments include syntheses of biologically relevant compounds in formamide solutions (98)(99)(100)(101)(102)(103)(104)(105)(106)(107)(108)(111)(112)(113)(114)(115), photosynthesis/photoselection of natural nucleotides (120)(121)(122)133), montmorillonite-catalyzed formation of long RNA oligomers (118) and membrane vesicles (134), RNA polymerization in the eutectic phase in water-ice (135), abiotic UV photosynthesis of the tricarboxylic acid cycle intermediates at ZnS (83,84) and TiO 2 crystals (136), as well as UV-triggered recharging of ADP to ATP (137). Further experimental exploration of models that mimic the conditions at anoxic geothermal fields are expected to shed more light on precellular evolution.…”

Section: Discussionmentioning

confidence: 99%

“…Specifically, it has been shown that silica minerals catalyze the formation of adenine and cytosine from formamide (103,111) and that TiO 2 , the main component of the mineral rutile, could catalyze the formation not only of purine derivatives but also of thymine, 5-hydroxymethyluracil, and even acyclonucleosides (112). Even widespread iron oxides have been shown to catalyze the synthesis of nucleobases from formamide (113). d) Spontaneous polymerization events, which are thermodynamically unfavorable in the bulk water, would be favored at geothermal fields.…”

Section: Terrestrial Anoxic Geothermal Fields As Cradles For Earliestmentioning

confidence: 99%

Origin of first cells at terrestrial, anoxic geothermal fields

Mulkidjanian

Bychkov²,

Dibrova³

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

366

336

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All cells contain much more potassium, phosphate, and transition metals than modern (or reconstructed primeval) oceans, lakes, or rivers. Cells maintain ion gradients by using sophisticated, energydependent membrane enzymes (membrane pumps) that are embedded in elaborate ion-tight membranes. The first cells could possess neither ion-tight membranes nor membrane pumps, so the concentrations of small inorganic molecules and ions within protocells and in their environment would equilibrate. Hence, the ion composition of modern cells might reflect the inorganic ion composition of the habitats of protocells. We attempted to reconstruct the "hatcheries" of the first cells by combining geochemical analysis with phylogenomic scrutiny of the inorganic ion requirements of universal components of modern cells. These ubiquitous, and by inference primordial, proteins and functional systems show affinity to and functional requirement for K + , Zn 2+ , Mn 2+, and phosphate. Thus, protocells must have evolved in habitats with a high K + /Na + ratio and relatively high concentrations of Zn, Mn, and phosphorous compounds. Geochemical reconstruction shows that the ionic composition conducive to the origin of cells could not have existed in marine settings but is compatible with emissions of vapor-dominated zones of inland geothermal systems. Under the anoxic, CO 2 -dominated primordial atmosphere, the chemistry of basins at geothermal fields would resemble the internal milieu of modern cells. The precellular stages of evolution might have transpired in shallow ponds of condensed and cooled geothermal vapor that were lined with porous silicate minerals mixed with metal sulfides and enriched in K + , Zn 2+, and phosphorous compounds.

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“…5,6 Because the one-pot synthesis from FM can give both purines and pyrimidines, 7, [12][13][14][15][16][17][18][19][20][21][22] it is reasonable to expect that a free radical route also leads to pyrimidines. In this context, we set out to perform quantum chemical computations to investigate the generation of nucleobases such as cytosine, uracil and thymine from FM, and the small species which were present in the prebiotic atmospheres (in particular of Titan) such as HCN,…”

Section: Introductionmentioning

confidence: 99%

Radical Pathways for the Prebiotic Formation of Pyrimidine Bases from Formamide

et al. 2015

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The prebiotic formation of nucleobases, the building blocks of RNA/DNA, is of current interest. Highly reactive radical species present in the atmosphere under irradiation have been suggested to be involved in the prebiotic synthesis of nucleobases from formamide (FM). We studied several free radical reaction pathways for the synthesis of pyrimidine bases (cytosine, uracil, and thymine) from FM under cold conditions. These pathways are theoretically determined using density functional theory (DFT) computations to examine their kinetic and thermodynamic feasibilities. These free radical reaction pathways share some common reaction types such as H-rearrangement, (•)H/(•)OH/(•)NH2 radical loss, and intramolecular radical cyclization. The rate-determining steps in these pathways are characterized with low energy barriers. The energy barriers of the ring formation steps are in the range of 3-7 kcal/mol. Although DFT methods are known to significantly underestimate the barriers for addition of (•)H radical to neutral species, many of these reactions are highly exergonic with energy release of -15 to -52 kcal/mol and are thus favorable. Among the suggested pathways for formation of cytosine (main route, routes 7a and 1a), uracil (main route, routes 7b and 1b), and thymine (main route and route 26a), the main routes are in general thermodynamically more exergonic and more kinetically favored than other alternative routes with lower overall energy barriers. The reaction energies released following formation of cytosine, uracil, and thymine from FM via the main radical routes amount to -59, -81, and -104 kcal/mol, respectively. Increasing temperature induces unfavorable changes in both kinetic and thermodynamic aspects of the suggested routes. However, the main routes are still more favored than the alternative pathways at the temperature up to the boiling point of FM.

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Formation of Nucleobases from Formamide in the Presence of Iron Oxides: Implication in Chemical Evolution and Origin of Life

Cited by 32 publications

References 38 publications

Photocatalytic degradation of polycyclic aromatic hydrocarbon benzo[a]pyrene by iron oxides and identification of degradation products

Photocatalytic degradation of polycyclic aromatic hydrocarbon benzo[a]pyrene by iron oxides and identification of degradation products

Origin of first cells at terrestrial, anoxic geothermal fields

Radical Pathways for the Prebiotic Formation of Pyrimidine Bases from Formamide

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