Aqueous Aerosols in Prebiotic Chemistry

Aqueous Aerosols in Prebiotic Chemistry

Author: Shaun Scally

A core topic in prebiotic chemistry research is the search for plausible synthetic routes that connect the building blocks of living organisms. Albert Eschenmoser proposed the “glyoxylate scenario”, in which glyoxylate and its formal dimer, dihydroxyfumarate, are key chemical starting materials of a possible metabolic system. These compounds serve as a source of the main biomonomers, such as sugars, amino acids, pyrimidines, and the constituents of the reductive tricarboxylic acid cycle (rTCAC). In this scenario, the stem compound is HCN, but as of yet, there are no examples that prove the production of glyoxylate from HCN as originally suggested by Eschenmoser.

Marta Ruiz-Bermejo and colleagues, Centro de Astrobiología, Madrid, Spain, have explored several syntheses of HCN polymers, together with statistical methods, as a step to elucidating the synthetic problem of the origin of life. They paid particular attention to the role of the aqueous aerosols. To do this, they designed a bubble-aerosol-droplet cycle for solutions of NH4CN or NaCN at pH 9.2, using an ultrasonic aerosol generator. The system was maintained at a constant temperature (38 °C) with active aerosol generation for 3 or 30 days, under atmospheric pressure or anoxic conditions (N2 atmosphere).

The synthesized HCN polymers were analyzed by gas chromatography–mass spectrometry (GC-MS). The researchers identified, for the first time, glyoxylic acid in these polymers, together with some constituents of the rTCAC, amino acids, and several N-heterocycles. The findings support the “glyoxylate scenario” hypothesis and suggest that aqueous aerosols could play an important role in prebiotic chemistry.


 

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