title: The isolation and characterization of the high-molecular-weight glycoprotein from pig colonic mucus.
abstract: 1. A high-molecular-weight glycoprotein constitutes over 80% by weight of the total glycoprotein from water-soluble pig colonic mucus. 2. It was isolated from from nucleic acid and non-covalently bound protein by nuclease digestion followed by equilibrium centrifugation in a CsCl gradient. 3. The glycoprotein has the following composition by weight: fucose 10.4%; glucosamine 23.9%; galactosamine 8.3%; sialic acid 9.9%; galactose 20.8%; sulphate 3.0%; protein 13.3%; moisture about 10%. 4. The native glycoprotein has the high mol.wt. of 15 X 10(6). 5. Reduction of the native glycoprotein with 2-mercaptoethanol results in a glycoprotein of mol.wt. 6 X 10(6). 6. Pronase digestion removes 29% of the protein (3% of the glycoprotein) but none of the carbohydrate. 7. The molecular weight of the Pronase-digested glycoprotein is 1.5 X 10(6), which is halved to 0.76 X 10(6) on reduction with 2-mercaptoethanol. 8. The contribution of non-covalent interactions, disulphide bridges and the non-glycosylated peptide core to the quaternary structure of the glycoprotein are discussed and compared with the known structure of pig gastric glycoportein.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002499:Centrifugation, Density Gradient; D055598:Chemical Phenomena; D002621:Chemistry; D003106:Colon / Q000378:metabolism*; D006023:Glycoproteins / Q000302:isolation & purification; D007419:Intestinal Secretions / Q000032:analysis*; D008623:Mercaptoethanol; D008970:Molecular Weight; D009093:Mucus / Q000032:analysis*; D011402:Pronase; D013552:Swine
chemical_list: D000596:Amino Acids; D006023:Glycoproteins; D008623:Mercaptoethanol; D011402:Pronase