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. 2013 Oct 7;110(44):17732–17737. doi: 10.1073/pnas.1312329110

Fig. 4.

Fig. 4.

Enhanced copying fidelity of an RNA template containing 2-thioU in place of U. (A) Scheme for nonenzymatic primer extension on UCUC (or sUCsUC) RNA templates. Red segment indicates newly formed phosphoramidate bonds. (B) PAGE analysis of primer extension products. Primer extension reactions were carried out as in Fig. 1. The reaction was initiated by addition of 5.0 mM 3′-NH2-2-MeImpddG and 10.0 mM 3′-NH2-2-MeImpddA. Arrows indicate primer and full-length product. (C) High-resolution MS analysis of the full-length extension products from a reaction of 100 pmol primer extended on a UCUC RNA template for 12 h followed by ethanol precipitation. There are four distinct major families of isotopic peaks for four different 14-mer full-length N+4 products, corresponding to A3G1, A2G2, A1G3, and G4, respectively. (D) High-resolution MS analysis of the full-length extension products from copying a sUCsUC RNA template. The major peak corresponds to the N+4 full-length product A2G2.