Molecular size determination of a membrane protein in surfactants by light scattering

• Published in: Biochimica et biophysica acta Vol. 1615; no. 1; pp. 69 - 76
• Main Authors: Aivaliotis, Michalis, Samolis, Panagiotis, Neofotistou, Elefteria, Remigy, Herve, Rizos, Apostolos K., Tsiotis, Georgios
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 02.09.2003
• Subjects: Chlorobi - chemistry; Chlorobium tepidum; Chromatography, High Pressure Liquid; Light; Light scattering; Membrane Proteins - chemistry; Molecular size; Outer surface protein; Surface-Active Agents; SDS-PAGE; Chlorobium tepidum; Light scattering; Molecular size; DLS; Octyl-POE; DDM; Outer surface protein; Hecameg; Triton X-100
• ISSN: 0005-2736; 0006-3002; 1879-2642; 1878-2434
• DOI: 10.1016/S0005-2736(03)00208-6

The molecular size of an outer surface protein from the photosynthetic bacterium Chlorobium tepidum was studied by dynamic light scattering (DLS) and HPLC gel filtration. For that purpose, the membrane protein was isolated and studied in four different nonionic surfactants, namely t-octylphenoxypolyethenoxyethanol (Triton X-100), (methyl-6- O-( N)-heptyl-carbamoyl)-α- d-glucopyranoside (Hecameg), dodecyl-β- d-maltoside (DDM) and n-octyl-oligo-oxyethylene (Octyl-POE). The protein was isolated by solubilization of the membranes with Triton X-100. The final purification step was a gel filtration, which was also used for surfactant exchange. Light scattering reveals the simultaneous presence of particles of different sizes in the 3–6 and 20–110 nm range, respectively. The smaller size is related to the hydrodynamic radius of the individual protein/surfactant complexes, whereas the larger size is associated with the presence of complex aggregates.