We measured the mixing enthalpies of gangliosides with methylated albumin in aqueous solutions at various concentration ratios, and carried out X-ray, neutron scattering experiments for the mixed solutions at nearly the same concentration ratios. The mixing heats were positive when the mixing ratios of lipid to protein inclined to either side, and negative at the intermediate range of the mixing ratio corresponding to the formation of interfacial fluff in a binary solution reported by Hayashi. The X-ray and neutron scattering analyses of the mixed solutions showed that addition of methylated albumin induces disintegration of the micelle structure of gangliosides and patchlike binding of ganglioside molecules to the albumin molecule appears. The analyses also showed that origomeric particles of the lipoproteins are formed at the intermediate range of the mixing ratios.