Comparison of the Dissociation Kinetics of the Streptavidin-Biotin Interaction in Solution and in the Gas Phase

摘要

From a comparison of structure and stability of biological complexes in their solvated and desolvated states, it is possible to gain new insights into the role of solvent in molecular recognition. Here, we report on thermal rate constants measured for the dissociation of gaseous ions of high affinity protein-ligand complexes composed of wild type or mutant forms of the homotetrameric protein streptavidin (S_(4)) and their small molecule ligand biotin (B). The contribution of solvent reorganization to the kinetic barrier for biotin loss was evaluated from a comparison of the Arrhenius activation parameters (Ea, A) determined for the desolvated complexes and parameter reported the corresponding complexes in neutral aqueous solutions.