Alkyl glucosides as effective solubilizing agents for bovine rhodopsin. A comparison with several commonly used detergents

The suitability of octyl and decyl-β-d-glucoside as solubilizing agents for the bovine retinal rod outer segment disc membrane was investigated and compared to that of hexadecyltrimethylammonium bromide, $\text{N,N-}\text{dimethyldodecylamine}$ oxide, Emulphogene BC-720 and digitonin. The properties measured included the thermal stability of rhodopsin, regenerability of bleached rhodopsin by addition of $\text{11-cis-}\text{retinal}$, and the rate of denaturation of bleached rhodopsin as measured by changes in the ultraviolet CD spectrum. Denaturing tendencies of the detergents were also evaluated by observing their effects on the absorption and CD spectra of sperm whale metmyoglobin. Our results demonstrate that octyl glucoside is superior to the other detergents, with the possible exception of digitonin, by the above criteria. Unlike digitonin, however, octyl glucoside affords rapid solubilization of the disc membrane and is itself highly soluble. Decyl glucoside has properties equivalent or superior to octyl glucoside, but salts and buffers interfere with its ability to solubilize the disc membrane. The well defined chemical composition, ease of removal by dialysis, and non-denaturing properties of the alkyl glucosides make them attractive detergents for membrane research.