Prebiotic Sugar Formation Under Nonaqueous Conditions and Mechanochemical Acceleration

Abstract

Monosaccharides represent one of the major building blocks of life. One of the plausible prebiotic synthesis routes is the formose network, which generates sugars from C1 and C2 carbon sources in basic aqueous solution. We report on the feasibility of the formation of monosaccharides under physical forces simulated in a ball mill starting from formaldehyde, glycolaldehyde, DL-glyceraldehyde as prebiotically available substrates using catalytically active, basic minerals. We investigated the influence of the mechanic energy input on our model system using calcium hydroxide in an oscillatory ball mill. We show that the synthesis of monosaccharides is kinetically accelerated under mechanochemical conditions. The resulting sugar mixture contains monosaccharides with straight and branched carbon chains as well as decomposition products. In comparison to the sugar formation in water, the monosaccharides formed under mechanochemical conditions are more stable and selectively synthesized. Our results imply the possibility of a prebiotic monosaccharide origin in geochemical environments scant or devoid of water promoted by mechanochemical forces such as meteorite impacts or lithospheric activity.

Mechanochemistry for Synthesis

“…[78] Thediscovery of efficient enzyme reactivity without bulk solvents is consistent with the emergent realization that mechanochemical reactivity could have strongly affected the development of living systems,including the formation of small prebiotic molecules. [79] 5. Light and Milling…”

Proto‐Urea‐RNA (Wöhler RNA) Containing Unusually Stable Urea Nucleosides

“…We know that formaldehyde and Ca(OH) 2 can give sugars by the formose reaction, as first described by Butlerov . Although it remains unclear how exactly such a process could lead to the substantial accumulation of ribose on the early Earth, recent developments have led to significant improvements in the prebiotic synthesis of ribose from simpler aldoses . We also know that urea was one of the most likely nitrogen‐containing molecules present on the early Earth and that it can activate mineral phosphate to achieve phosphorylations .…”

Proto‐Urea‐RNA (Wöhler RNA) Containing Unusually Stable Urea Nucleosides

“…[48] As discussed, biuret and triuret are obtained upon pyrolysis of urea, one of the most likely building blocks available on the early Earth. Given that various tri-, tetra-, and pentose sugars are prebiotically accessible from glycoaldehyde, [31,32] which is itself accessible from either formaldehyde [30] or HCN by ultraviolet irradiation, [49] our discovery creates the prebiotically attractive possibility of generating information-encoding oligomers whose key building blocks are derived of simple one-carbon units.The chemistry described here now needs to be explored with sugars simpler than ribose.D iscussed examples are threose- [22,50] and glycol-based [23,25] backbones.…”

“…[22] TNAw as later simplified to an acyclicp olymer known as glycol nucleic acid (GNA), [23][24][25] and various other XNAb ackbones have since been investigated. [31][32][33] We also know that urea was one of the most likely nitrogen-containing molecules present on the early Earth and that it can activate mineral phosphate to achieve phosphorylations. [30] Although it remains unclear how exactly such aprocess could lead to the substantial accumulation of ribose on the early Earth, recent developments have led to significant improvements in the prebiotic synthesis of ribose from simpler aldoses.…”

“…[30] Although it remains unclear how exactly such aprocess could lead to the substantial accumulation of ribose on the early Earth, recent developments have led to significant improvements in the prebiotic synthesis of ribose from simpler aldoses. [31][32][33] We also know that urea was one of the most likely nitrogen-containing molecules present on the early Earth and that it can activate mineral phosphate to achieve phosphorylations. [4,5] As urea itself has even been shown to react directly with ribose under mildly acidic conditions, [34] we asked whether the construction of informational base-pairing systems based on the pyrolysis products of urea, biuret and triuret (Figure 1b), [35] would be possible.…”