Protein-surfactant interaction: differences between fluorinated and hydrogenated surfactants.

The interactions of proteins with fluorinated/hydrogenated surfactants were investigated by circular dichroism and turbidity measurement. Pairs of fluorinated and hydrogenated surfactants with similar critical micelle concentrations (cmc), including sodium perfluorooctanoate/sodium decylsulfate and lithium perfluorononanoate/sodium dodecylsulfate were compared in view of their interactions with proteins including BSA, lysozyme, beta-lactoglobulin and ubiquitin. It was found that fluorinated surfactants exhibited stronger interactions with proteins than hydrogenated ones, which, however, depended on the structures of both proteins and surfactant molecules.

Interaction between lysozyme and mixtures of cationic-anionic surfactants decyltriethylammonium bromide-sodium decylsulfonate.

The interaction of lysozyme with the mixtures of cationic-anionic surfactants decyltriethylammonium bromide-sodium decylsulfonate (C10NE-C10SO3) was investigated by turbidity, circular dichroism (CD) and lysozyme activity assay. At pH 3.0, the mixtures of C10NE-C10SO3 formed precipitates with lysozyme at a wide range around the equal molar ratio of C10NE to C10SO3.

Interactions of beta-lactoglobulin with sodium decylsulfonate, decyltriethylammonium bromide, and their mixtures.

The interactions of beta-lactoglobulin (BLG) with anionic surfactant sodium decylsulfonate (C10SO3), cationic surfactant decyltriethylammonium bromide (C10NE), and the mixtures of cationic-anionic surfactants (C10NE-C10SO3) were investigated by circular dichroism (CD) and fluorescence methods. At pH 7.0, C10NE and the C10NE-rich surfactant mixtures of C10NE-C10SO3 could form precipitates with BLG, while C10SO3, equimolar mixtures of C10NE-C10SO3, or C10SO3-rich mixtures of C10NE-C10SO3 form homogeneous solutions with BLG.

Effect of cationic surfactants on the interaction between sodium perfluorooctanoate and beta-lactoglobulin.

The interaction between the fluorocarbon surfactant, sodium perfluorooctanoate (SPFO), and beta-lactoglobulin (BLG) was studied. In particular, the effects of cationic surfactants, such as alkyltriethylammonium bromide (C(n)NE, n=8, 10, 12), on SPFO-BLG interaction were examined. It was shown that the anionic fluorocarbon surfactant, SPFO, was a strong denaturant of BLG.

Interaction between bovine serum albumin and equimolarly mixed cationic-anionic surfactants decyltriethylammonium bromide-sodium decyl sulfonate.

The interactions of bovine serum albumin (BSA) with the anionic surfactant sodium decylsulfonate (C10SO3), the cationic surfactant decyltriethylammonium bromide (C10NE) and equimolarly mixed cationic-anionic surfactants C10NE-C10SO3 were investigated by surface tension, viscosity, dynamic light scattering (DLS) and circular dichroism (CD). It was shown that the single ionic surfactant C10SO3 or C10NE has obvious interaction with BSA. The presence of C10SO3 or C10NE modified BSA structure.

Surfactant-induced refolding of lysozyme.

The surfactant-lysozyme interaction was investigated by circular dichroism, fluorescence, UV, dynamic light scattering, surface tension, turbidity measurements and lysozyme activity assay. A new way of refolding of lysozyme was found. It was shown that the lysozyme unfolded by anionic surfactants could be renatured by adding cationic surfactants.