Effect of microenvironment created by surfactant on superoxide dismutase activity

The activity of SOD (superoxide dismutase) catalyzing dismutation of supero xide radical anion O-2(-) was studied by a modified NBT (nitroblue tetrazol ium) method in aqueous solution, micellar solutions and lamellar liquid cry stals (LLC) consisting of the surfactants CTAB and TX-100. The experiments showed that the inhibition by SOD of NET reduction in organized assemblies of surfactants was weaker than in aqueous solution. The order of inhibition was as follows: in phosphate buffer (pH = 7.8) > in TX-100 micelle > in CT AB micelles > in TX-100 LLC > in CTAB LLC. The results were explained by de crease of alpha -helical content in SOD and difficulty in the transformatio n of SOD configurations in organized assemblies of surfactant, as well as b y catalytic effects of micelles on NBT reduction.