DISSOCIATION,AGGREGATION OF SESAME α-GLOBULIN IN NONIONIC DETERGENT SOLUTION

Nonionic detergents Triton X-100 and Brij 36T induce dissociation and aggregation of the protein sesame α-globulin above the critical micelle concentrations (cmc) of the detergents. Spectrophotometric titration in Triton shows no change in the pK_Int value of the tyrosyl groups at 1 × 10^-3M detergent where both dissociation and aggregation of the protein are observed. Fluorescence measurement does not indicate any change in the environment of the tryptophan groups of the protein in Brij. Viscosity measurements show no major conformational change of the protein in the detergent solution. Binding measurements suggest that perhaps micelles of the detergent predominantly bind to the protein. The detergent micelles preferentially bind to the exposed hydrophobic surfaces of the protein subunits. The association of the protein detergent complex through electrostatic interaction is probably responsible for the formation of the aggregates.