Enzyme activity and stability control by amphiphilic self-organizing systems in aqueous solutions

The interaction of surfactants with proteins in aqueous solutions has been the subject of many investigations to understand the interactions between m embrane proteins and lipids, structurally similar to synthetic surfactants. The effect of surfactant on enzyme structure and activity is the result of chemically selective interactions that may be influenced both by the enzym e structure and by the chemistry of the surfactant. For many years, surfact ants have been considered as non-specific denaturants of proteins, even if in the literature several of them are reported to enhance activity and/or s tability of some enzymes: the detergent can interact with the enzyme and ca use a conformational change to a more active form and/or stabilize its nati ve folded structure. Although the surfactant head group seems to have a det ermining role, other structural features of the detergent are also importan t in influencing the catalytic properties of an enzyme, i.e. head group siz e and its hydrophobic/hydrophilic balance. Up to now it is very difficult t o predict the molecular features of the surfactant and an extensive investi gation on the relationship between the surfactant chemical structure and th e catalytic properties of enzyme is still required. (C) 2000 Elsevier Scien ce Ltd. All rights reserved.