Isolation of detergent-solubilized monomers of bacteriorhodopsin by size-exclusion high-performance liquid chromatography.

Bacteriorhodopsin, an integral membrane protein of purple membranes, was solubilized with n-octylglucoside and isolated as intact monomeric micelles by high-performance size-exclusion chromatography. It was shown that separation was obtained between these micelles and either those containing bacterio-opsin or retinal as well as bacterio-opsin in the aggregated state. Estimates of the apparent molecular weights and Stokes radii were obtained by comparison with water-soluble proteins with known properties. Thermal denaturation of the native protein micelle induced the formation of a denatured species, which was similar to that found from denaturation at 4 degrees C.