Synthesis and Degradation of Nucleobases and Nucleic Acids by Formamide in the Presence of Montmorillonites

About a Formamide-Based Origin of Informational Polymers: Syntheses of Nucleobases and Favourable Thermodynamic Niches for Early Polymers

“…At moderately hot temperatures (in our experimental settings between 90°and 160°C, Saladino et al 2001Saladino et al , 2003Saladino et al , 2004bSaladino et al , 2005b this pristine little pond would quickly be enriched by nucleic bases and, if TiO 2 was also present, by sugar chains growing onto them (Saladino et al 2003). How widespread might have been the photochemistry at the basis of this latter process has not been thoroughly studied; however, it can be confidently assumed that additional catalysts might have also been able to carry out similar synthetic processes.…”

“…Let us further imagine that water slips into the dry (Van Holde 1980) phosphate-clay crevice in which the nucleic bases have formed (Saladino et al 2001, 2004b, Saladino et al 2005b) and have been (trans)-phosphorylated (Schoffstall 1976, Schoffstall et al 1982, Schoffstall and Laing 1985, Schoffstall and Mahone 1988, thus binding one to the other. The question is: how long will the polymers survive in the water solution in Orig Life Evol Biosph (2006) 36:523-531 which they dissolve and in which they are supposed to endure for a while long enough to replicate and start their evolutionary endeavour?…”

“…a Degradation or removal of the nucleic base leads to the destabilization of the sugar ring, followed by β-elimination (at 3′ or at 5′) Saladino et al 2004bSaladino et al , 2005a. b The first part of the hydrolysis may occur via nucleobase degradation (pathway A) or nucleobase substitution (pathway B).…”

“…The prebiotic synthesis of cytosine from a one-carbon precursor as simple as NH 2 CHO is straightforward and opens a novel prebiotic pathway to purine and pyrimidine nucleobases simply by changing the catalyst used in the condensation. A few examples: uracil, cytosine, hypoxantine (a bioisoster of guanine), 4-aminoimidazole-5-carboxamide (AICA) and 4-formylaminoimidazole-5-carboxamide (fAICA) are obtained (in addition to purine and adenine) by heating NH 2 CHO in the presence of the montmorillonites K-10, K-30, KSF and of aluminum-pillared clays, (compounds differing for pore size distribution, surface area, acidity and cation exchange capability - Saladino et al 2004b). It is noteworthy that the ribosyl-5′-monophosphate derivatives of AICA, fAICA and hypoxantine are the main intermediates in the actual biosynthesis of inosine 5′-monophosphate (IMP), the precursor of adenosine 5′-monophosphate (AMP) through the action of a formyltransferase and IMPcyclohydrolase.…”

AB INITIO Simulations of Desorption and Reactivity of Glycine at a Water-Pyrite Interface at “Iron-Sulfur World” Prebiotic Conditions

“…Refs. (Bernal, 1951;von Kiedrowski, 1996;Fry, 2000;Severin, 2000;Hazen, 2001;Dörr et al, 2003;Saladino et al, 2004), enjoys fresh impetus, partly in view of the stimulating work of Wächtershäuser (Wächtershäuser, 1988a;Wächtershäuser, 1992), which is however controversially discussed (de Duve and Miller, 1991;Bada and Lazcano, 2002;Wächtershäuser, 2002).…”