Light-scattering studies of fractionated ovine submaxillary mucins

Static and dynamic light-scattering studies of solutions of ovine submaxillary mucin (OSM) glycoproteins, fractionated by exclusion chromatography on Sephacryl S-1000, are reported. These experiments yielded information regarding the structure and conformation of the glycoprotein chain, in the form of weight-average molecular weights, Mw, z-average radius of gyration, Rg,z, and z-average of the inverse hydrodynamic radius, (Rh-1)z. The values of (Rh-1)z are found to correlate very well with the S-1000 elution volume characteristics for four OSM fractions of different molecular weights. The structural parameters for these OSM fractions are, within experimental error, similar to those deduced for porcine submaxillary mucins (PSM) in earlier studies. The results suggest that, like PSM, the glycoprotein structure of OSM consists of linear chains constructed by covalently linking two or more elementary subunits together via disulfide bonds. In addition, the rigidity of the protein core of OSM is substantially greater than that observed for non-glycosylated-polypeptide random coils. Because (Rh-1)z, and hence, elution volume depends only on the molecular weight of the mucin protein core, the Mw calibration obtained for OSM should be applicable to the chromatography of other mucin glycoproteins.