Biotecnologia Aplicada Elfos Scientiae ISSN: 0684-4551 Vol. 12, Num. 3, 1995, pp. 176

REPORTE CORTO / SHORT REPORT

CONFORMATIONAL SUBSTATES IN PROTEINS: TWO-DIMENSIONAL ANALYSIS OF THE POLARIZED INTENSITY DECAYS OF THE TRYPTOPHAN FLUORESCENCE EMISSION BYTHE MAXIMUM ENTROPY METHOD

Michel Vincet^1, Nikolai Vekshin^2 and Jacques Gallay^1

^1L.U.R.E.: Laboratoire pour l'Utilisation du Rayonnement Electromagnetique, Centre National de la Recherch e Scientifique, Ministere de l'Enseignement Superieur et de la Recherche, Commisariat a l'Energie Atomique, Centre Universitaire d'Orsay, 91405, France. ^2Institute of Biophysics of Cell, Moscow Region, 142292, Pushchino, Russia.

Code Number: BA95068
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The heterogeneity of the tryptophan (Trp) fluorescence emission of several proteins containing a single tryptophan residue, either embedded in the interior of the protein matrix or freely accessible to the solvent, was studied by the time-correlated single photon counting technique. The data of the polarized components of the fluorescence emission were analyzed by the Maximum Entropy Method in one dimension (excited-state lifetimes t) and two dimensions (excited-state lifetimes t and rotational correlations times q). The 2D analysis of the Trp fluorescence emission clearly shows a correlation between the shortest excited state lifetime and the fastest motion. The existence of slowly exchanging conformational substates with different packing constraints affecting the indole subnanosecond mobility can be suggested in specific cases.

Copyright 1995 Sociedad Iberolatinamericana de Biotecnologia Aplicada a la Salud