Lipids, prebiotic synthesis

Prebiotic synthesis likely contributed to the spectrum of compounds in a relative early phase of the Earth since exposure of methane and water to brush discharges resulted in the formation of monocarboxylic acids up to a length of 12 carbon atoms. The fact that essential lipids do have optical activity might indicate that they are of meteoritic origin. 

The competition among protocells for membrane components could drive rapid evolution of sophisticated membranes. While fatty acids were likely to be available through prebiotic synthesis, the synthesis of phospholipids may have required enzymatic activity, such as a ribozyme that could catalyse condensation of fatty acids with phosphate head groups. If such an activity arose, protocells containing phospholipids would be able to hold on to their fatty acids more tightly, in the sense that the rate constant for dissociation of the fatty acids from the bulk phase is reduced by the presence of the bipartite lipid. In addition, the dissociation rate for bipartite lipids themselves is also much lower than that of fatty acids. Both effects... 

First, the question of where nucleotide monomers may have come from is critical. Given that the formose reaction is the most likely candidate for the synthesis of prebiotic ribose, but yields very little pure material, the role of stereoselective catalysts (clays, amino acids, or lipid aggregates) in directing the reaction should be fully explored. In this respect, Wachters-hauser16 has advanced a scheme for nucleotide synthesis based on pyrite catalysis than can be readily tested. 

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