Contribution of capillary zone electrophoresis to the analysis of cecal mucins

The ability of capillary electrophoresis to perform the separation of mucin glycoforms has been investigated. Adsorption of mucins to the capillary was observed in most cases, leading to unreproducible results. This was due in part to the characteristic structure of mucin (highly charged, large size) and also to its poor solubility. Various buffers were therefore investigated; it was found that a zwitterionic electrolyte, such as a (3-[cyclohexylamino]-1-propanesulfonic acid) (CAPS) buffer, pH 8.8, greatly improved the separation. Using this buffer, mucin was resolved into five main fractions. The use of several additives, such as cationic molecules (1,4-diaminobutane [DAB]) or hydrophilic polymers (hydroxypropylmethylcellulose [HPMC], polyethylene glycol [PEG]) was also investigated. PEC and HPMC did not affect the separation and the electroosmotic flow (EOF) in the same manner. The favorable effect of the addition of PEC was clearly demonstrated and it was postulated that some interaction of this polymer with the mucins occurred. Finally, the application of the method to the comparison of glycoform patterns of mouse cecal mucins showed a marked difference for mucins derived from two sources: germ-free and gnotobiotic mice. These results indicate that mucins from gnotobiotic mice have been degraded due to the glycosidic activity of the bacterial strains present in these mice.