@article { ISI:000366339700024,
	title = {Cosolvent effects on solute-solvent hydrogen-bond dynamics: ultrafast 2D IR investigations},
	journal = {Journal of Physical Chemistry B},
	volume = {119},
	number = {49},
	year = {2015},
	month = {DEC},
	pages = {15334-15343},
	publisher = {AMER CHEMICAL SOC},
	type = {Article},
	address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA},
	abstract = {<p>Cosolvents strongly influence the solute-solvent interactions of biomolecules in aqueous environments and have profound effects on the stability and activity of several proteins and enzymes. Experimental studies have previously reported on the hydrogen-bond dynamics of water molecules in the presence of a cosolvent, but understanding the effects from a solute{\textquoteright}s perspective could provide greater insight into protein stability. Because carbonyl groups are abundant in biomolecules, the current study used 2D IR spectroscopy and molecular dynamics simulations to compare the hydrogen-bond dynamics of the solute{\textquoteright}s carbonyl group in aqueous solution, with and without the presence of DMSO as a cosolvent. 2D IR spectroscopy was used to quantitatively estimate the time scales of the hydrogen-bond dynamics of the carbonyl group in neat water and 1:1 DMSO/water solution. The 2D IR results show spectral signatures of a chemical exchange process: The presence of the cosolvent was found to lower the hydrogen-bond exchange rate by a factor of 5. The measured exchange rates were 7.50 X 10(11) and 1.48 X 10(11) s(-1) in neat water and 1:1 DMSO/water, respectively. Molecular dynamics simulations predict a significantly shorter carbonyl hydrogen-bond lifetime in neat water than in 1:1 DMSO/water and provide molecular insights into the exchange mechanism. The binding of the cosolvent to the solute was found to be accompanied by the release of hydrogen-bonded water molecules to the bulk. The widely different hydrogen-bond lifetimes and exchange rates with and without DMSO indicate a significant change in the ultrafast hydrogen-bond dynamics in the presence of a cosolvent, which, in turn, might play an important role in the stability and activity of biomolecules.</p>},
	issn = {1520-6106},
	doi = {10.1021/acs.jpcb.5b08643},
	author = {Kashid, Somnath M. and Jin, Geun Young and Bagchi, Sayan and Kim, Yung Sam}
}
