Berlin 2005 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 25: Biological systems I

CPP 25.4: Talk

Tuesday, March 8, 2005, 14:45–15:00, TU C230

Local Compressibilities of Proteins Reveal the Coupling Between Protein and Solvent Dynamics — •Christina Scharnagl and Josef Friedrich — TU München, Fakultät für Physik E14, 85350 Freising

We carry out molecular dynamics simulations of cytochrome c (cyt c) in different solvents and under different external pressure. From the volume fluctuations we calculate intrinsic compressibilities. We show that the intrinsic compressibility values capture the collective correlation of local volume fluctuations with volume fluctuations in the surrounding protein-solvent system. Therefore, properties probed by a local sensor reflect also the coupling between protein and solvent dynamics.

In cyt c the heme chromophore is the local probe in optical experiments which report the low compressibility value of 0.05 1/GPa in glycerol/water (3:2 v/v) solvent. The simulations reveal that glycerol as a cosolvent decouples the volume fluctuations of the protein core from the hydration shell, while the application of high pressure reduces the localized volume fluctuations drastically. To both external perturbations, the protein responds with a reduction of its intrinsic compressibility.