Determination of molecular weight of membrane proteins by the use of low-angle laser light scattering combined with high-performance gel chromatography in the presence of a non-ionic surfactant

Abstract

An assessment study was carried out to evaluate the performance of the low-angle laser light scattering technique combined with high-performance gel chromatography in the presence of a nonionic surfactant, octaethyleneglycol n-dodecyl ether, precision differential refractometry and ultraviolet photometry. It was found that the combined technique is highly promising as a method for the determination of the molecular weight of a membrane protein solubilized by the surfactant. For trial, molecular weights of the following membrane proteins of Escherichia coli, both solubilized in oligomeric forms, were measured; porin that forms the transmembrane diffusion pore in the outer membrane, and λ-receptor protein that facilitates the diffusion of maltose-maltodextrins across the outer membrane. The result obtained indicates that both porin and λ-receptor protein exist as trimers in the surfactant solution.