Effects of monohydration on an adenine-thymine base pair

We analyzed the monohydration effect on the hydrogen-bonded structure between the adenine-thymine base pair using path integral molecular dynamics simulations including the nuclear quantum and thermal effects. We focused on two monohydration models for an adenine-thymine base pair with a water molecule bound to each adenine and thymine site. The adenine-thymine base pair without a water molecule was also discussed to reveal the role of a water molecule in monohydrated models. We found that the monohydration effect varies depending on the location of the water molecule. The monohydration effect on the inter-molecular motions is also investigated using the principle component analysis. The monohydration alters the inter-molecular motions of adenine-thymine base pair. We found that the nuclear quantum effect on the motion depends on the positions of the bound water molecule. The nuclear quantum effect on the hydrogen-bonded structure of adenine, thymine and water molecules is rather small, but we found significantly large nuclear quantum effect on the inter-molecular motions of the monohydrated base pair systems.