8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

P2.86Tue 611:23-14:00Theoretical study of protein hydration thermodynamicsbased on the 3D integral equation theory of molecularliquid and the spatial decomposition analysisTakeshi Yamazaki 1 and Andriy Kovalenko 11 National Institute for Nanotechnology, 11421 Saskatchewan Drive, T6G 2M9, Edmonton,CanadaAnalysis of a protein typically begins with an attempt to decompose its complexity into a setof fundamental units. Once such units are extracted and investigated, one may proceed withreconstructing the protein from these units to understand it as a whole. Therefore, decompositionstrategies are essential and indispensable in every field related to protein science. We have proposedthe method of spatial decomposition analysis (SDA) based on 3D integral equation theory ofmolecular liquid (3D-RISM) to study and decompose the solvation thermodynamics of solute intoatomic level contributions. The 3D-RISM theory maps the solvation thermodynamic properties,such as the solvation free energy, onto the 3D space around the solute, including the excluded volumeof the solute, with the elementary volume contributions expressed in terms of the 3D total anddirect correlation functions. By utilizing this feature, the SDA breaks down the thermodynamicproperty into the partial contributions from the volume elements attributed to the solute fragments(functional groups or residues) based on the proximity criterion to the 3D-RISM mapping. Wehave applied SDA to the process of complexation of β-cyclodextrin and 1-adamantanecarboxylicacid in water, and showed that the adamantyl group of 1-adamantanecarboxylic acid is responsiblefor the complexation rather than its carboxyl group. In this presentation, we apply SDA to the hydrationthermodynamics of miniproteins and decompose their hydration free energy into the partialcontributions of each residue. The results show that SDA is capable of detecting a change in theprotein thermodynamics due to local conformational changes and mutations. We will also discussabout the SDA result of temperature and pressure effects on the protein hydration thermodynamics.[1] Yamazaki, T. ; Kovalenko, A. J. Chem. Theory Comput. 2009, 5, 1723-1730.[2] Yamazaki, T. ; Kovalenko, A. J. Phys. Chem. B, 2011, 115, 310-318.86