Microhydration of Guanine Base Pairs

摘要

Water plays an important role in the structure and function of DNA and RNA.Recent theoretical calculations show that for the AT base pair,the presence of two water molecules suffices to stabilize a stacked structure more than a hydrogen-bonded structure.The enhanced stabilization results from the water molecules surrounding the base pair and creating a bridge between the bases.Calculations predict that for GG base pairs about 20% of the structures will stack upon addition of two water molecules.Additional water further stabilizes stacking structures,and upon addition of a fourth water molecule 90% of the structures are predicted to be stacked.Sivanesan et al.predict that five or six water molecules preferentially stabilize GC pairs.Microhydration also can stabilize specific tautomers.In solution,bulk solvent hides the details of these interactions,but by isolating the bases and sequentially adding single solvent molecules it is possible to study the changes caused by microscopic solvent effects on base interactions.