An analysis of the heterogeneity of mucins. No evidence for a self-association

There are two possible contributions to the heterogeneity of mucus glycoproteins as observed in the analytical ultracentrifuge: firstly, from associative phenomena, and, secondly, from a polydisperse distribution of non-interacting species of different molecular masses. It is shown from the non-superposability of plots of point-weight-average relative molecular masses against concentration for differing initial cell-loading concentrations that polydispersity must be significant. It is further shown, by attempting to block any associative phenomena by competitive inhibition of potential sites for hydrophobic inter-particle interaction, that the observed heterogeneity is primarily a result of polydispersity and not a self-association.