Dr Seishi Shimizu
01904 328281
E-mail: seishi.shimizu@york.ac.uk
Solution Chemistry and Statistical Thermodynamics
1. Molecular theory of solubility
Solubility is crucial in chemical engineering. Without reasonable solubility, many chemical processes do not work, yet the difficulty in choosing appropriate solvents (or solvent mixtures) is costing the industry heftily. In addition, environmental concerns increasingly compel the use of "greener" alternative solvents. Thus solution chemistry is finally coming back to spotlight it deserves.
Can we understand solubility from basic molecular interactions? Why do some additives (cosolvents) increase the solubility? What is the molecular mechanism of solvation? To such questions, simple and basic physical data (such as density and activity) give surprisingly effective answer. This is made possible by a rigorous and exact theory of statistical mechanics.
2. Thermodynamics of protein solvation
Water is the basis of molecular biology and biochemistry: Not only because it occupies 60-70% of our body weight, but also because of its active role in the structure, function, and stability of biological macromolecules. In addition, there are various salts and organic molecules surrounding the macromolecules. These solvent molecules significantly influence the stability, folding and binding equilibria of proteins.
There are various cosolvent molecules around the proteins affecting their stability. Sugars and polyols are used to protect proteins from stabilization. Urea and guanidine destabilize proteins. Salts have varying degree of effects on protein stability (Hofmeister effect). How can we understand the effect of such cosolvents on protein stability? This is indeed an old question. We have developed a theory which can answer such questions at a molecular level.
3. Statistical thermodynamics of solution.
All above is possible only through a decent theory, which can bridge solubility / equilibria / folding to basic molecular interactions. I have developed a rigorous and exact theory, based upon a long tradition of statistical thermodynamics. Two sets of experiments would be sufficient: dependence on cosolvent concentration and the accompanying change in volume. This exact theory enables one to calculate the solute-solvent and solute-cosolvent interactions from such basic experimental data.
Selected Publications
- Estimating hydration changes upon biomolecular reactions from osmotic
stress, high pressure, and preferential hydration experiments.
S Shimizu, Proc Natl Acad Sci, 2004, 101, 1195-1199. - The Hofmeister effect and protein-salt interactions.
S Shimizu, W L McLaren and N Matubayasi, J Chem Phys, 2006, 129, 234905. - Hydrophilicity, the major determining factor influencing the solvation environment of protic ionic liquids.
L Wright, M W Sanders, L Tate, G Fairless, L Crowhurst, N C Bruce, A J Walker, G A Hembury and S Shimizu, Phys Chem Chem Phys, 2010, 12, 9063-9066. - Unexpected preferential dehydration of artemisinin in ionic liquids.
M W Sanders, L Wright, L Tate, G Fairless, L Crowhurst, N C Bruce, A J Walker, G A Hembury and S Shimizu, J Phys Chem A, 2009, 113, 10143-10145. - The Kirkwood-Buff theory and the effect of cosolvents on biochemical reactions.
S Shimizu and C L Boon, J Chem Phys, 2004, 121, 9147-9155. - Temperature dependence of three-body hydrophobic interactions: Potential
of mean force, enthalpy, entropy, heat capacity, and nonadditivity.
M S Moghaddam, S Shimizu, and H S Chan, J Am Chem Soc, 2005, 127, 303-316. - Configuration-Dependent Heat Capacity of Pairwise Hydrophobic Interactions.
S Shimizu and H S Chan, J Am Chem Soc, 2001, 123, 2083-2084. - Alcohol Denaturation: Thermodynamic Theory of Peptide Unit Solvation.
S Shimizu and K Shimizu, J Am Chem Soc, 1999, 121, 2387.
