Determination of electrokinetic and hydrodynamic parameters of proteins by modeling their electrophoretic mobilities through the electrically charged spherical soft particle

Abstract

This work explores the possibility of using the electrically charged "spherical soft particle" (SSP) to model the electrophoretic mobility of proteins in the low charge regime. The general framework concerning the electrophoretic mobility of the SSP already presented in the literature is analyzed and discussed here in particular for polyampholyte-polypeptide chains. In this regard, this theory is applied to BSA for different protocol pH values. The physicochemical conditions required to model proteins as SSP from their experimentally determined electrophoretic mobilities are established. In particular, the protein charge regulation phenomenon and the SSP particle core are included to study BSA having isoelectric point pI ≈ 5.71, within a wide range of bulk pH values. The results of this case study are compared with previous ones concerning the spherical porous particle and the spherical hard particle with occluded water. A discussion of chain conformations in the SSP polyampholyte layer is presented through estimations of the packing and friction fractal dimensions.

Determination of electrokinetic and hydrodynamic parameters of proteins by modeling their electrophoretic mobilities through the electrically charged spherical porous particle

“…In these regards, SSP electrophoretic mobility models presented by Ohshima for the low charge regime are useful, where the particle core is present and the flow of the BGE solution in the polyampholyte layer is allowed. In , we study the electrophoretic mobility of BSA through the SSP model for different pH values to visualize this protein denaturation in the presence of a particle core. In this regard, it must be observed that experimentally measured mobilities of proteins are necessary for the determination of their electrokinetic and hydrodynamic parameters.…”

“…Thus, the use of SPP is an appropriate starting point to model a protein electrophoretic mobility within the wider framework of the SSP, allowing, in principle, to assign a polypeptide hydration uniformly distributed in the whole particle. We present the application of the SSP to the modeling of electrophoretic mobility of polypeptides in .…”

“…This work is organized as follows. In Section , some theoretical aspects involving the electrophoretic mobility modeling of the general electrically charged SSP are described for the purposes of visualizing those corresponding to the SPP as a particular case of the SSP and for a clear presentation of the general framework in . Thus, the simple case of a SPP may be useful at this stage to establish the interplay between the physicochemical properties of proteins and particle characteristic parameters when a = 0.…”

“…In this framework, the estimation of polypeptide properties through particles models is relevant once the AAS is known. Therefore, in this work and following one , we have the target of analyzing different particles (SPP and SSP) to obtain as main result the particle–solvent friction for different chain conformations. Then this parameter may be interpreted through the “hydrated chain fractal” model (as it was done for the AHP in ) to evaluate the packing and friction fractal dimensions of polypeptide chains, which in turns are crucial to examine polypeptide global conformations and scaling laws at different pH values.…”

“…Then this parameter may be interpreted through the “hydrated chain fractal” model (as it was done for the AHP in ) to evaluate the packing and friction fractal dimensions of polypeptide chains, which in turns are crucial to examine polypeptide global conformations and scaling laws at different pH values. These scaling laws relate chain electrophoretic mobility to intrinsic viscosity, diffusion and sedimentation coefficients, and particle permeability in different polypeptide conformational states . In fact, the values of friction fractal dimension are shown below to be sensitive to the type of particle used to cover the collapsed to free draining chain states.…”