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

Cheatham, T E; Crowley, M F; Fox, T; Kollman, P A · Proc Natl Acad Sci U S A · 1997

basic_science · Level V

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Abstract

Advances in computer power, methodology, and empirical force fields now allow routine "stable" nanosecond-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 approximately 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.

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