Swiss albino mouse brain gangliosides: biophysical studies

The brain gangliosides mixture of Swiss albino mice were studied from a biophysical viewpoint. The value of v found was 0.577 ml/g. The isoelectric point gave a value of 1.50, which is in agreement with the presence of sialic acid groups. The isoionic point, 2.76, is close to the pKa for sialic acid. The number average molecular weight determined in the presence of ions was 229000, while in the absence of ions it was 78000, this weight suggesting a low degree of aggregation. The[eta] value of 3.56 and 4.84 in both the presence and absence of ions would indicate an asymmetrical micelle and/or more solvate than a rigid or impermeable sphere. The value of S020, w in the presence of ions was 9.19, while in their absence it was 7.65, corresponding to a lower molecular weight coincident with that found for Mn. Hydrodynamic relations permit the supposition that the brain gangliosides mixture of Swiss albino mice is not a symmetrical micelle, since the frictional and symmetry ratio found is equal to 1.29, which corresponds to an axial ratio of 6. The value of D is equal to 2.30 X 10(-7) cm2/sec; this fact is even more suggestive that we are not dealing with a symmetrical micelle. It was not possible to calculate the molecular weight using equations under the assumption that gangliosides are a spherical micelle. It was concluded that they might be a prolate ellipsoid of revolution.