Effects of Water Deuteration on Thermodynamic and Structural Properties of Proteins and Biomembranes

Light and heavy water are often used interchangeably in spectroscopic experiments with the tacit assumption that the structure of the investigated biomolecule does not depend too much on employing one or the other solvent. While this may often be a good approximation, we demonstrate here using molecular dynamics simulations incorporating nuclear quantum effects via modification of the interaction potential that there are small but significant differences. Namely, as quantified and discussed in the present study, both proteins and biomembranes tend to be slightly more compact and rigid in D₂O than in H₂O, which reflects the stronger hydrogen bonding in the former solvent.