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

Fig. 1.

Fig. 1.

Nonenzymatic primer extension reactions on homopolymeric templates. (A) Structure of an internucleotide linkage in N3′-P5′–linked phosphoramidate DNA (3′-NP-DNA). (B) General primer extension reaction scheme showing a 5′-Cy3–labeled 3′-amino–terminated DNA primer annealed to a complementary chimeric DNA/3′-NP-DNA template. The 3′-NH2-2-MeImpddN monomers extend the primer by four nucleotides on the complementary template forming a chimeric DNA/3′-NP-DNA product. Red lines indicate phosphoramidate bonds. (C) PAGE analysis of primer extension products on indicated 3′-NP-DNA templates. Primer extension reactions contained 0.1 µM Cy3-labeled-3′-amino–terminated DNA primer, 0.5 µM template, 100 mM Mes-CAPS-Hepes, pH 7.5, and 100 mM 1-(2-hydroxyethyl)imidazole (HEI). The reactions were initiated by addition of 5.0 mM 3′-NH2-2-MeImpddG, 5.0 mM 3′-NH2-2-MeImpddC, and 10.0 mM 3′-NH2-2-MeImpddA, respectively. Arrows indicate the primer and the full-length product (+4).