Sugar-Driven Prebiotic Synthesis of Ammonia from Nitrite

Abstract

Reaction of 3-5 carbon sugars, glycolaldehyde, and α-ketoaldehydes with nitrite under mild anaerobic aqueous conditions yielded ammonia, an essential substrate for the synthesis of nitrogen-containing molecules during abiogenesis. Under the same conditions, ammonia synthesis was not driven by formaldehyde, glyoxylate, 2-deoxyribose, and glucose, a result indicating that the reduction process requires an organic reductant containing either an accessible α-hydroxycarbonyl group or an α-dicarbonyl group. Small amounts of aqueous Fe +3 catalyzed the sugar-driven synthesis of ammonia. The glyceraldehyde concentration dependence of ammonia synthesis, and control studies of ammonia's reaction with glyceraldehyde, indicated that ammonia formation is accompanied by incorporation of part of the synthesized ammonia into sugar-derived organic products. The ability of sugars to drive the synthesis of ammonia is considered important to abiogenesis because it provides a way to generate photochemically unstable ammonia at sites of sugar-based origin-of-life processes from nitrite, a plausible prebiotic nitrogen species.

Abundant ammonia in primitive asteroids and the case for a possible exobiology

“…On the early Earth, on the other hand, the prebiotic inventory of reduced nitrogen necessary for the formation of N-containing biomolecules has been difficult to predict. Although the hypotheses of a reducing atmosphere had initially allowed one to envision a considerable ammonia abundance as well as evolutionary pathways for the production of amino acids (e.g., by Miller-type processes, 19), the current geochemical evidence of a neutral early Earth atmosphere (20 and references therein) combined with the known photochemical destruction of ammonia (21) has left prebiotic scenarios struggling to account for a constant provision of ammonia (22,23). An abundant exogenous delivery of ammonia, therefore, might have been significant in aiding early Earth's molecular evolution toward prebiotic syntheses and the data in this study, showing the capability of some asteroidal bodies to provide it, would make a reasonable case for exobiology.…”

Amino acid analogues provide multiple plausible pathways to prebiotic peptides

“…Weber found the formation of glycine-thiodepsipeptides and N -acetyl-S-lactoylcysteine, considered as energy-rich prebiotic molecules [40,41]. In 1998, Weber investigated the role of mercaptan in the synthesis of alanine and homoserine catalysed by formaldehyde and glycolaldehyde, revealing mercaptan as a catalyst for the formation of alanine and homoserine [42]. The study also showed the formation of amino acid thioester, a precursor to thiodepsipeptides.…”

The Major Transitions of Life from a Network Perspective

“…One way to possibly overcome this difficulty is to seek to define the structural basis that can enable certain behaviors that we associate with life. In this sense, it is still useful to examine the various definitions of life because they often include elements from complexity and non-linear dynamics (Weber, 2010). For example, Macklem and Seely (2010) recently proposed the following definition: “Life is a self-organizing, self-regulating, self-reproducing, interconnected, open thermodynamic network of component parts existing in a complex regime in the phase transition between order and chaos as a plant, animal, microbe or fungus.” Obviously, one can argue about the details and a possible minimal set of the list (Trifonov, 2011) or the elusiveness of a convergent theme (Tirard et al, 2010).…”