Protein stability induced by ligand binding correlates with changes in protein flexibility

CELEJ MS, MONTICH GG, FIDELIO GD.

PROTEIN SCIENCE

Protein Society

Año: 2003 vol. 12 p. 1496 - 1496

0961-8368

he interaction between ligands and proteins usually induces changes in protein thermal stability with modifications in the midpoint denaturation temperature, enthalpy of unfolding, and heat capacity. These modifications are due to the coupling of unfolding with binding equilibrium. Furthermore, they can be attained by changes in protein structure and conformational flexibility induced by ligand interaction. To study these effects we have used bovine serum albumin (BSA) interacting with three different anilinonaphthalene sulfonate derivatives (ANS). These ligands have different effects on protein stability, conformation, and dynamics. Protein stability was studied by differential scanning calorimetry and fluorescence spectroscopy, whereas conformational changes were detected by circular dichroism and infrared spectroscopy including kinetics of hydrogen/deuterium exchange. The order of calorimetric midpoint of denaturation was:1,8-ANS-BSA > 2,6-ANS-BSA > free BSA >> (n