Protein Translational Diffusion and Intermolecular Interactions of Globular and Intrinsically Unstructured Proteins

Abstract

The study of intermolecular interactions of proteins has been an important problem for many years. This paper presents an approach to analyze different levels of protein interactions in solutions through a set of the secondand higher-order virial coefficients. The proposed approach is based on the diversified analysis of protein translational collective diffusion and self-diffusion obtained by dynamic light scattering and the pulsed-field gradient NMR (PFG NMR) spectroscopy experimental data. The experimental results were analyzed within the theoretical approach based on Vink's frictional formalism of nonequilibrium thermodynamics and the standard Derjaguin−Landau−Verwey−Overbeekb (DLVO) theory of interactions of colloid particles in electrolyte solutions. The second-and higher-order virial coefficients were obtained to estimate the pairwise and many-body intermolecular interactions in the solutions of globular α-chymotrypsin and intrinsically unstructured α S -casein. The second virial coefficients were calculated from the model of the protein−protein potential of mean force. The description of protein−protein interactions includes a set of interaction potentials: the attractive charge−dipole, dipole−dipole, the dispersion Hamaker, the mean force osmotic-attraction, and the repulsive charge−charge ones. It has been found that the major contribution to the intermolecular α S -casein interactions is made by the repulsive charge−charge potential, whereas for the case of α-chymotrypsin, the contributions from other types of interaction are of importance. It was determined that the model was well suited to describe the interactions of both globular and intrinsically disordered proteins. The suggested combination of Vink's approach and the DLVO theory is novel and holds much promise to make a profound analysis of the processes in systems containing various types of protein molecules.

Understanding the interaction of proteins to ion exchange chromatographic supports: A surface energetics approach

“…This theory has also been used to study bovine serum interaction to different solid surfaces 33 . This theory has also been modified to study protein–protein interaction 34,35 …”

“…33 This theory has also been modified to study protein-protein interaction. 34,35 All these studies suggest that the surface energetics approach, utilizing XDLVO theory, has the potential to understand protein interaction to ion exchange chromatographic supports, which has never been attempted earlier. Hence, this study is an attempt to find out the interaction behavior of proteins to ion exchange chromatographic material by XDLVO theory/surface energetics approach.…”

The Role of pH and Ionic Strength in the Attraction–Repulsion Balance of Fibrinogen Interactions

“…To realize the knob-hole contacts, the fibrin molecules have to approach each other to make possible a more or less parallel orientation (Figure 2) defined by the weak nonspecific interactions such as the electrostatic repulsion and the van der Waals attraction. 18,25 In the case of the elongated asymmetric Fg molecules, these interactions are "amplified" due to the nonspherical asymmetry of charge distribution and interactions between point electric charges and their dipoles. 18,26,27 An important role of weak interactions is to control a relatively long-ranged attraction−repulsion balance leading to a parallel orientation of the Fg molecules and further fibrin polymerization 28 (Figure 2).…”

“…Early, we have shown that the shape of concentration dependence for the protein collective diffusion manifests a current balance between different weak interprotein interactions. 25,39,44,45 The experimental data on the protein collective diffusion as a function of the volume fraction φ is possible to present with a set of virial coefficients 46…”

“…47,48 However, despite a fairly common practice to analyze molecular interactions by means of virial coefficients, 49−54 there is no quantitative relationship between the intermolecular interaction potential and the virial coefficients with the order higher than the second one, A 2 . The second virial coefficient A 2 can be determined by means of the total pair interaction potential W, defined within the McMillan−Mayer theory for cylindrical particles as 18,25,[49][50][51]55…”