A molecular level picture of the stabilization of A-DNA in mixed ethanol-water solutions

Advances in computer power, methodology, and empirical force fields now allow routine ''stable'' nano-second-length molecular dynamics simulations of DNA in water, The accurate representation of environmental influences on structure remains a major, unresolved issue, In contrast to simulations of A-DNA in water (where an A-DNA to B-DNA transition is observed) and in pure ethanol (where disruption of the structure is observed), A-DNA in approximate to 85% ethanol solution remains in a canonical A-DNA geometry as expected, The stabilization of A-DNA by ethanol is likely due to disruption of the spine of hydration in the minor groove and the presence of ion-mediated interhelical bonds and extensive hydration across the major groove.