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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-23 17:59 |
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Conference: Bucharest University Faculty of Physics 2002 Meeting
Section: Electricity and Biophysics: Honorary Session Dedicated to Professors: Victor Gheorghe (Head of the Dept. 1972-1984) and Grigore Turcu
Title:
Parameters of Interaction Between Proteins
and Their Specific Ligandns, Determined by
Isothermal Titration Calorimetry
Authors:
Aurel I. Popescu1 and Constantin T. Craescu2
Affiliation:
1. Faculty of Physics, University of Bucharest, Romania.
2. INSERM, U 350, Institut Curie, Section de Biologie, Centre Universitaire 91 405 Orsay, France.
E-mail
Keywords:
Abstract:
The interaction between the proteins and their specific ligands can be studied by different biophysical methods (e.g. NMR, circular dichroism,etc.). But the only method, at the same time, very sensitive, rapid and versatile is the Isothermal Titration Calorimetry (ITC). By this method, a ligand is successively injected in small amounts in a measure cell containing the protein solution in a much smaller concentration. The interaction between the two molecules is accompanied either by the liberation (exothermic reaction) or absorption (endothermic reaction) of heat. The peaks of heat involved during the successive injections are recorded by a precision microcalorimeter (in our case, New Hampton ITC, USA). By integrated each heat peak and by fitting the experimental points, the ORIGIN soft is offering the following parameters: the affinity constant (Ka), the enthalpy of reaction (DH) and reaction stoichiometry (n). The variation of entropy (DS) and of Gibbs free energy (DG) can be computed, indicating if a reaction is enthalpically or entropically driven.
In the present work, the reaction parameters in the case of three couples protein-ligand (Calcium Vector Protein-Melittin, Centrine-synthetic ligands, UMP Kinase-UTP) are presented and commented. (UMP = Uridin MonoPhosphate, UTP = Uridin TriPhosphate).
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