Density functional theory reveals an increase in the amino H1 chemical shift in guanine due to hydrogen bonding with water

Abstract

Electronic structure calculations underestimate the chemical shift of the non H-bonded amino proton 1H22 in isolated G-quartet structures. The current work shows that this underestimation is due to the absence of a water environment in the calculations: coordination of at least two water molecules is required to obtain good agreement with experiment. The results indicate how improved agreement between calculated and experimental (solution-phase) NMR data can be obtained.