Neutron scattering from ganglioside micelles

Abstract

Dilute solutions of ionic micelles formed by a biological glycolipid (the ganglioside GM1) have been investigated at various ionic strengths by small angle neutron scattering. The size and shape of the GM1 micelle is not appreciably affected by added salt concentration in the range 0–100 mMNaCl. Despite the fact that the solute concentration is below 0.5 %, with no added salt the structure factor shows a pronounced peak at a value k _m which roughly corresponds to 2π/d, where d is the interparticle distance. From the height of peak we derive the electric charge Z of the micelle by fitting the data with a theoretical calculation which uses a screened Coulomb potential for the intermicellar interaction, and the hypernetted chain approximation for the calculation of the radial distribution function. The experimental k _m is somewhat larger than the theoretical one. This effect could be connected with the nonsphericity of GM1 micelles.