Impact of intermolecular attraction and repulsion on molecular diffusion and virial coefficients of spheroidal and rod-shaped proteins

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

“…The Fg molecule is made up of two sets of threefold polypeptide binders (Aα, Bβ, and γ) 2 integrated by 29 disulfide bonds. 17,18 Fibrin assembly is initiated by conversion of fibrinogen to fibrin through the action of serine protease thrombin, which cleaves fibrinopeptides A and B from the N-termini of fibrinogen. 19−22 is a prelude for the Fg self-assembly into the two-stranded fibrin oligomers by means of the knob-hole contacts 23,24 (Figure 2).…”

“…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).…”

“…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). Whereas the thrombin-catalyzed fibrin network has been investigated in detail, 6,29−31 much less is known of the weak long-range interfibrinogen interactions in the absence of thrombin.…”

“…33,34 Near the isoelectric point, the proteins have a small net charge, and therefore, the electrostatic repulsion between molecules is minimized making contributions from hydrogen bonding and van der Waals forces more substantial. 18,35,36 Although the physiological values of pH and ionic strength are clearly defined for biological systems, 32,37,38 the study of Fg−Fg interactions in a distinct electrolyte environment can clarify various steps of Fg functioning.…”

“…In the previous article, 18 our multistaged diffusive approach was applied to determine nonspecific interactions of rodshaped Fg in comparison with spheroidal α-chymotrypsin. In the present work, the influence of solution pH and ionic strength on the Fg intermolecular interactions has been investigated.…”