Dresden 2006 – scientific programme
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CPP: Chemische Physik und Polymerphysik
CPP 28: Biological Systems
CPP 28.6: Talk
Friday, March 31, 2006, 11:45–12:00, ZEU Lich
Solvent induced forces on bio-molecules — •Hendrik Hansen-Goos1,2, Roland Roth1,2, Klaus Mecke3, and Siegfried Dietrich1,2 — 1MPI für Metallforschung, Heisenbergstr. 3, 70569 Stuttgart — 2ITAP, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart — 3ITP, Universität Erlangen-Nürnberg, Staudtstr. 7, 91058 Erlangen
Understanding conformations of complex molecules in organisms requires to account for solvent induced forces. The most elementary of these being the depletion force which arises even in absence of internal energy contributions from a system’s tendency to maximise entropy. Additionally, solvent-solvent and solvent-molecule interactions can strongly influence the conformation of the solved molecule. A first step towards the understanding of depletion forces is the Asakura-Oosawa (AO) model which neglects solvent-solvent interactions. More realistic solvent models like the hard-sphere fluid or attractive (water-like) solvents can be realised within the context of morphological thermodynamics recently put forward. The approach is based on the Hadwiger theorem which implies that (under certain assumptions) the change in free energy upon insertion of a molecule into the solvent is a linear function of the molecule’s Minkowski measures with interaction specific coefficients. We introduce a self-consistent scaled particle calculation yielding quasi-exact coefficients for the hard-sphere fluid. The morphological approach is applied for different interactions, illustrating that conclusions drawn from the AO model for phenomena such as helix formation are somewhat misleading. Limits of the approach are discussed by comparison with density functional theory calculations.