Structural Changes of AOT Reverse Micelles by the Presence of Proteins: Percolation Process Induced by Cytochrome C

The formation of reverse micelles in non polar solvents have been investigated for many years [1,5]. The presence of water is necessary to form a large surfactant aggregate: close packing of the surfactant polar heads leaves an empty volume in the center of the micellar core which can only be filled with hydration (or bound) water. The reverse micelles considered here are then also microemulsions. We will not make differences between the terms swollen micelles and microemulsions, although certain authors use the first term for systems containing only bound water. For AOT, the maximum amount of bound water in the micelles correspond to a water-surfactant molar ratio w = [H2O]/[AOT] of about 10. Above this amount, part of the water is “free”. Because AOT is soluble in many non polar solvents over a wide range of concentrations, a large number of studies of the structure of reverse micelles have been made with this surfactant.