Structural and electronic property responses to the arsenic/phosphorus exchange in GC-related DNA of the B-form

Abstract

The suggestion that phosphorus/arsenic replacement in DNA can play a role in living things has generated great controversy (Wolfe-Simon et al., Science 2011, 332, 1163). Examined here theoretically are substitution effects on Watson-Crick base pairing and base stacking patterns in realistic DNA subunits. Using duplex DNA models deoxyguanylyl-3',5'-deoxycytidine ([dGpdC](2) ) and deoxycytidyly-3',5'-deoxyguanosine ([dCpdG)](2) ), this research reveals that the geometric variations caused by the As/P exchange are small and are limited to the phosphate/arsenate groups. As/P replacement leads to alterations of ∼0.15 Å in P/AsO bond lengths and less than 1.5° variations in OP/AsO angles. The Watson-Crick base pairing and base stacking patterns are independent of the As/P replacement. The vertical electron detachment energies are also largely unaffected. However, the electron capture ability of the DNA units is improved by the As substitution. The arsenate is found to be the main electron acceptor in As-DNA. The results are relevant to the possible existence of viable As-DNAs, at least in the guanine and cytosine (GC)-related B-form DNA.