Solubility of Membrane Proteins in Aqueous Media

Human red blood cell ghosts are severely disrupted by the removal of inorganic cations, and in the presence of 5 x 10-3 m EDTA or 0.1 m (CH3)4NBr the membrane proteins are almost totally soluble in aqueous media without the use of detergents or organic solvents. These soluble proteins have been partially fractionated by column chromatography as a preliminary step to studying their physical and functional properties. Optical rotatory dispersion spectra indicate no major conformational change upon removal of the proteins from the insoluble lipid in the solvent systems studied. Preliminary investigation of porcine cerebral myelin and bovine heart inner mitochondria suggest that the interaction between lipid and protein differs in these two systems from that in the human erythrocyte membrane.