Electronic Journal of Biotechnology ISSN: 0717-3458
© 2000 by Universidad Católica de Valparaíso -- Chile
ORAL PRESENTATION

Changes in Protein Dynamics and Stability Observed by Tryptophan Fluorescence and Phosphorescence

F. Tölgyesi*
Institute of Biophysics and Radiation Biology
Semmelweis University of Medicine, Budapest H-1444 P.O.B. 263
Hungary
E-mail: tolgyesi@puskin.sote.hu

B. Ullrich, M. Laberge
Institute of Biophysics and Radiation Biology
Semmelweis University of Medicine, Budapest H-1444 P.O.B. 263
Hungary
E-mail: tolgyesi@puskin.sote.hu

J. Fidy
Institute of Biophysics and Radiation Biology
Semmelweis University of Medicine, Budapest H-1444 P.O.B. 263
Hungary
E-mail: tolgyesi@puskin.sote.hu

* Corresponding author


Oral Presentation

Tryptophan fluorescence and phosporescence studied as a function of temperature carry information about protein conformation, dynamics and stability. Especially two parameters, the relaxation time determined from red edge excitation of fluorescence and phosphorescence lifetime give valuable insight into the changes in the dynamics of the tryptophan environment and through this into stability of the molecule. We investigated these parameters for several proteins from cryogenic temperatures up to the physiological range. We observed the characteristic change in protein dynamics at a low temperature, around 200 K, that is already known, but we observed another change at a physiological temperature, around 30°C, from phosphorescence lifetime measurements, that can be interpreted as the activation of large amplitude motions in the protein. Examples will be given, how the observed parameters signal changes in protein dynamics and stability with complex formation (e.g. HIV1 protease with its inhibitor) or with aggregation (e.g. bovine lens a-crystallin).

Supported by UNESCO / MIRCEN network
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