Figure 1.

Schematic representation of recent advances in nonenzymatic primer extension. (a) Homopolymeric RNA templates copied using activated 2′-amino-2′-3′-dideoxynucleotides within fatty acid vesicles at low Mg²⁺ concentration, generating an N2′–P5′-linked phosphoramidate polymer. (b) Homopolymeric RNA templates copied using activated ribonucleotides within fatty acid vesicles in the presence of citrate-chelated Mg²⁺, generating an RNA polymer. (c) Chemical structure of ribonucleotides activated with 2-aminoimidazole. Activated trinucleotides catalyze primer extension and allow for the one-pot copying of RNA templates containing all four nucleotides. R signifies either hydrogen for activated mononucleotides, or dinucleotides for activated trimers. (d) Imidazolium-bridged intermediate responsible for efficient primer extension. R is either a hydrogen or a dinucleotide. (e) Mixed-sequence RNA templates being copied using activated ribonucleotides and trinucleotides within fatty acid vesicles in the presence of citrate-chelated Mg²⁺.