Tetrathiafulvalene-Labelled Nucleosides and Nucleoside Triphosphates: Synthesis, Electrochemistry and the Scope of Their Polymerase Incorporation into DNA

The title 5-substituted pyrimidines (U and C) and 7-substituted 7-deazapurines (7-deazaA and 7-deazaG) bearing tetrathiafulvelene (TTF) attached through an acetylene linker have been prepared by Sonogashira cross-coupling of the corresponding 5- or 7-iodo derivatives of nucleosides with 2-ethynyltetrathiafulvalene. Their subsequent triphosphorylation gave the corresponding nucleoside triphosphates (dNTPs). Square-wave voltammetry of the TTF-labelled nucleosides and nucleotides showed two peaks, one at 0.2-0.3 V and the other at around 0.65 V (vs. Ag/AgCl/3 m KCl), which correspond to two reversible one-electron redox process in the TTF moiety. Polymerase incorporation of the TTF-labelled dNTPs into DNA has also been studied. Multiple incorporations were rather problematic and only by using dC(TTF)TP was efficient primer extension observed with Vent (exo-)polymerase. Single nucleotide extension was successful with labelled A (dA(center dot TTF)TP) and C (dC(TTF)TP) nucleotides. Inhibition of the polymerase was observed at higher concentrations of dN(TTF)TPs. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)