Anthraquinone as a redox label for DNA: synthesis, enzymatic incorporation, and electrochemistry of anthraquinone-modified nucleosides, nucleotides, and DNA

Modified 2'-deoxynucleosides and deoxynucleoside triphosphates (dNTPs) bearing anthraquinone (AQ) attached through an acetylene or propargylcarbamoyl linker at the 5-position of pyrimidine (C) or at the 7-position of 7-deazaadenine were prepared by Sonogashira cross-coupling of halogenated dNTPs with 2-ethynylanthraquinone or 2-(2-propynylcarbamoyl)anthraquinone. Polymerase incorporations of the AQ-labeled dNTPs into DNA by primer extension with KOD XL polymerase have been successfully developed. The electrochemical properties of the AQ-labeled nucleosides, nucleotides, and DNA were studied by cyclic and square-wave voltammetry, which show a distinct reversible couple of peaks around -0.4 V that make the AQ a suitable redox label for DNA.