Comment on "Characterization of the tunneling conductance across DNA bases"

In a recent article, Zikic {\it et al.} [Phys. Rev. E {\bf 74}, 011919 (2006)] present first-principles calculations of the DNA nucleotides electrical conductance. They report qualitative and quantitative differences with previous work, in particular with that of Zwolak and Di Ventra [Nano Lett. {\bf 5}, 421 (2005)] and Lagerqvist {\it et al.} [Nano Lett. {\bf 6}, 779 (2006)]. In this comment we address the alleged discrepancies and show that Zikic {\it et al.} have seriously misread and misunderstood the existing literature. In addition, we point out the deficiencies of their approach in calculating the conductance of nucleotides and the consequent erroneous conclusions they report.