The Use of Detergents for the Isolation of Intact Carrier Proteins, Exemplified by the ADP, ATP Carrier of Mitochondria

Abstract

In recent years, progress in handling detergents for the solubilization and isolation of integral membrane protein has been outstanding. Beginning in 1969, when our group embarked on the task of isolating and purifying the ADP, ATP carrier, no success was reached in the first 3 years because we used the then-popular methods for isolation of membrane proteins such as solubilization with cholate and deoxycholate combined with ammonium sulfate fractionation, organic solvents such as butanol, chloroethanol, lysolecithin, and even SDS (Klingenberg et al., 1974). Our objective was to isolate the membrane protein not only in a pure but also in the native state. Nonionic detergents were hardly used at that time, although they were already known to be excellent solubilizers of membranes. However, their use was not very popular, because they seemed difficult to handle during the purification; it seemed impossible to remove the large excess of detergent required for solubilization. Moreover, in several cases there was no clear assay for characterizing the protein in the native state.