The Eggers laboratory proposes to develop and test a thermodynamic framework for aqueous reaction equilibria that treats the solvent as a co-reactant. The new approach is motivated by the fact that the numbers and orientations of hydrogen bonds in liquid water are altered near a solute, and by the fact that the rearrangement in water structure, which accompanies the conversion of the traditional reactants to products, should be included in the total free energy change of the system. Although the solvent contribution may be negligible for chemical reactions involving formation and/or breakage of covalent bonds, changes in water structure may play a dominant role in binding equilibria and conformational equilibria. Consequently, this research is expected to enhance our understanding of the role of water in many important biological reactions, including protein folding and the structure of the polynucleic acids, DNA and RNA. A combination of biophysical techniques, including two types of calorimetry experiments, will be implemented to test the validity of the new framework. Enthalpy and entropy values of bulk water will be measured and tabulated for many solutions of interest, including neutral salts, osmolytes, chaotropes, and crowding agents. Application of the new framework to the solubility of model compounds should lead to a quantitative assessment of hydration forces in macromolecular structure. This research provides an alternative view for understanding the effects of solutes on biological equilibria, a view that may be deemed as more intuitive and more widely applicable than current models. In addition, this research may yield new insights into molecular recognition and drug design. The experimental data obtained from this work may be extremely useful to computational scientists in developing realistic force fields for water at interfaces, an important consideration for computer simulations of biological processes.

Public Health Relevance

This research aims to quantify the participation of water molecules in a few specific reactions that may be viewed as models for many of the key molecular events that occur in living cells. The basic findings will have implications for all of molecular and cellular biology, and, therefore, for all research involving human health and disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Continuance Award (SC3)
Project #
1SC3GM089591-01
Application #
7761779
Study Section
Special Emphasis Panel (ZGM1-MBRS-X (CH))
Program Officer
Okita, Richard T
Project Start
2010-01-01
Project End
2013-12-31
Budget Start
2010-01-01
Budget End
2010-12-31
Support Year
1
Fiscal Year
2010
Total Cost
$107,550
Indirect Cost
Name
San Jose State University
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
056820715
City
San Jose
State
CA
Country
United States
Zip Code
95112
Castellano, Brian M; Eggers, Daryl K (2013) Experimental support for a desolvation energy term in governing equations for binding equilibria. J Phys Chem B 117:8180-8
Eggers, Daryl K (2011) A bulk water-dependent desolvation energy model for analyzing the effects of secondary solutes on biological equilibria. Biochemistry 50:2004-12
Payumo, Alexander Y; Huijon, R Michael; Mansfield, Deauna D et al. (2011) Changes in apparent molar water volume and DKP solubility yield insights on the Hofmeister effect. J Phys Chem B 115:14784-8