title: Effect of rotation on the diffusion-controlled rate of ligand-protein association.
abstract: The rate of binding a fairly large ligand molecule to a protein is reduced below the usual diffusion-controlled rate by the requirement of a certain rotational orientation. A simple, approximate treatment of this effect is given for special cases of spherical and ellipsoidal ligands. As the center of an ellipsoidal ligand approaches a protein surface, there is an effective repulsive potential between ligand and surface owning to restricted rotation of the ligand. The frequency factor kT/h of the Eyring rate theory is replaced in these reactions involving diffusion in solution by D/Rlambda, where D = diffusion coefficient of ligand, lambda = thermal deBroglie wavelength of ligand, and R = "capture" distance around the binding site on the protein.
mesh_terms: D000327:Adsorption; D001665:Binding Sites; D004058:Diffusion; D008024:Ligands; D008433:Mathematics; D011485:Protein Binding; D011487:Protein Conformation; D011506:Proteins; D012399:Rotation
chemical_list: D008024:Ligands; D011506:Proteins