Prebiotic nucleic acids need space to grow

Abstract

What were the conditions on early Earth when nucleotides were formed, and what are the most plausible nucleoside candidates? Answering these questions will require mechanistic chemistry and planetary science to work together, enhancing not limiting each other's scope of investigation.

Fig. 1

Phosphorimidazolide activation of nucleotides. a Phosphorimidazolide mediated non-enzymatic template-directed RNA primer extension. b Prebiotically plausible synthesis of adenosine-5′-phosphorimidazolide (R = H), using a photochemically generated activating agent

Fig. 2

The roles of 2-aminoazoles in prebiotically plausible nucleotide chemistry. Green: Divergent synthesis of 2-aminothiazole (2AT), 2-aminooxazole (2AO) and 2-aminoimidazole (2AT) from cyanamide (1). Yellow: Crystallisation-controlled aldehyde sequestration by 2-aminothiazole (2AT) giving access to pure glycolaldehyde (GC) and glyceraldehyde (GA), in the order required for selective nucleotide synthesis, from equilibrating sugar mixtures. Pink: Prebiotically plausible pyrimidine nucleotide synthesis. Cytidine X = NH₂, uridine X = OH. Blue: Nucleoside-5′-phosphorimidazolide activation with 2-aminoimidazole (2AI). B = nucleobase