INTEC   05402
INSTITUTO DE DESARROLLO TECNOLOGICO PARA LA INDUSTRIA QUIMICA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Electrokinetic properties and global conformations of polypeptides from the modeling of their electrophoretic mobility data
Autor/es:
DEIBER, JULIO ALCIDES (CONFERENCISTA INVITADO)
Lugar:
Buenos Aires
Reunión:
Simposio; The 18th Latin-American Symposium on Biothecnology, Biomedical, Biopharmaceutical and Industrial Applications of Capillary Electrophoresis and Microchip Technology (LACE 2012); 2012
Institución organizadora:
UBA
Resumen:
The electrophoretic mobility of polypeptides in formulated BGE solutions depends on complex electrokinetic and hydrodynamic properties defined in relation to the topological structure of electrically charged polyampholyte heterochains. Most of the theoretical studies predicting polypeptide electrophoretic mobility consider particle models able to describe phenomena associated with electrical and hydrodynamic responses of the polyampholyte chain migration in an applied electrical field. In this framework the estimation of polypeptide effective charge, hydration, size and shape through particles models are relevant once the amino acid sequence is known. Therefore this work analyses different particles models (aspherical and spherical hard particles and spherical porous and soft particles) to obtain as main result the particle-solvent friction. Then this parameter is interpreted through the “Hydrated Chain Fractal” model (Deiber et al., 2011, 2012) to evaluate the packing and friction fractal dimensions of polypeptide chains, which in turns are crucial to analyze 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. It is also shown that polypeptide chains satisfy their functions in a pH different from the bulk pH where they are immersed. Thus there exists a regulated average pH in the chain domain depending on both its charge state and interaction with the BGE solvent. In general the charge regulation phenomenon pushes pH values toward the chain isoelectric point, indicating that the so-called bulk pH, regularly used to evaluate the protein charge state, requires further quantitative considerations. Here typical examples involving proteins and peptides are presented, and needs for future researches are highlighted. Certainly these results may have relevant impacts on protein functions in biological systems; for instance, aspects concerning optimal enzymatic performance and protein-ligand mechanisms