Kinetics and thermodynamics of protein adsorption: A generalized moleculartheoretical approach

F. Fang et I. Szleifer, Kinetics and thermodynamics of protein adsorption: A generalized moleculartheoretical approach, BIOPHYS J, 80(6), 2001, pp. 2568-2589
Citations number
Categorie Soggetti
Biochemistry & Biophysics
Journal title
ISSN journal
0006-3495 → ACNP
Year of publication
2568 - 2589
SICI code
The thermodynamics and kinetics of protein adsorption are studied using a m olecular theoretical approach. The cases studied include competitive adsorp tion from mixtures and the effect of conformational changes upon adsorption . The kinetic theory is based on a generalized diffusion equation in which the driving force for motion is the gradient of chemical potentials of the proteins. The time-dependent chemical potentials, as well as the equilibriu m behavior of the system, are obtained using a molecular mean-field theory. The theory provides, within the same theoretical formulation, the diffusio n and the kinetic (activated) controlled regimes. By separation of ideal an d nonideal contributions to the chemical potential, the equation of motion shows a purely diffusive part and the motion of the particles in the potent ial of mean force resulting from the intermolecular interactions. The theor y enables the calculation of the time-dependent surface coverage of protein s, the dynamic surface tension, and the structure of the adsorbed layer in contact with the approaching proteins. For the case of competitive adsorpti on from a solution containing a mixture of large and small proteins, a vari ety of different adsorption patterns are observed depending upon the bulk c omposition, the strength of the interaction between the particles, and the surface and size of the proteins. It is found that the experimentally obser ved Vroman sequence is predicted in the case that the bulk solution is at a composition with an excess of the small protein, and that the interaction between the large protein and the surface is much larger than that of the s maller protein. The effect of surface conformational changes of the adsorbe d proteins in the time-dependent adsorption is studied in detail. The theor y predicts regimes of constant density and dynamic surface tension that are long lived but are only intermediates before the final approach to equilib rium. The implications of the findings to the interpretation of experimenta l observations is discussed.