Great Britain Gel Filtration of Sialoglycoproteins

The role of sialic acid in the gel-filtration behaviour of sialoglycoproteins was investigated by using the separated isoenzymes of purified human liver a-L-fucosidase and several other well-known sialic acid-containing glycoproteins (fetuin, a,-acid glycoprotein, thyroglobulin and bovine submaxillary mucin). For each glycoprotein studied, gel filtration ofits desialylated derivative gave an apparent molecular weight much less than that expected just from removal of sialic acid. For the lower-molecular-weight glycoproteins (fetuin and a,-acid glycoprotein), gel filtration of the sialylated molecules led to apparent molecular weights much larger than thle known values. The dat'a indicate that gel filtration cannot be used for accurately determining the molecular weights of at least some sialoglycoproteins.