Regensburg 2002 – wissenschaftliches Programm

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SYBM: Physik biologischer Materie

SYBM 401: Physics of biological matter: Poster

SYBM 401.5: Poster

Dienstag, 12. März 2002, 18:00–19:30, H37

Unfolding experiments of cytochrome c: microscopic aspects — •Harald Lesch and Josef Friedrich — Lehrstuhl für Physik Weihenstephan, TU München, Vöttinger Str. 40, D-85350 Freising

During pressure and temperature induced denaturation of a modified cytochrome c protein a typical spectroscopic pattern is generated.

In the stable regime a pressure or temperature increase results in a red shift of the fluorescence. In this regime it is only the solvent shift which is modified. The solvent shift is mainly due to dispersive interactions.

As the transformation regime is approached the fluorescence shifts to the blue. The observed blue shift arises from electrostatic interactions, which are turned on as strongly polar groups approach the chromophore. Evidently, water molecules seem to come into close contact with the dye probe. The conclusion is that, in the transformation regime, water molecules enter the interior and cause a destabilization of the protein.

The experiment allows for a complete determination of the thermodynamic quantities involved in the transformation.