title: Effect of lipids and proteins on the viscosity of gastric mucus glycoprotein.
abstract: The effect of associated lipids and covalently bound fatty acids, and the contribution of serum albumin and secretory IgA to the viscosity of dog gastric mucus glycoprotein was investigated. Using a cone/plate viscometer at shear rates between 1.15 - 230s -1, it was found that extraction of associated lipids from the glycoprotein lead to 80-85% decrease in the viscosity. Further loss (39%) in viscosity of the delipidated glycoprotein occurred following removal of covalently bound fatty acids. Reassociation of the delipidated glycoprotein with its neutral lipids increased the viscosity 3-fold, a 2.5-fold increase was obtained with glycolipids, and 2-fold with phospholipids. Preincubation of purified mucus glycoprotein with albumin or IgA resulted in the increase in viscosity. This increase in viscosity was proportional to albumin concentration up to 10%, and to IgA concentration up to 5%. The results show that interaction of lipids and proteins with mucus glycoprotein contributes significantly to the viscosity of gastric mucus.
mesh_terms: D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D004285:Dogs; D005227:Fatty Acids / Q000378:metabolism; D005753:Gastric Mucosa / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism*; D007071:Immunoglobulin A, Secretory / Q000378:metabolism; D050356:Lipid Metabolism; D009093:Mucus / Q000378:metabolism*; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*; D012709:Serum Albumin / Q000378:metabolism; D014783:Viscosity
chemical_list: D005227:Fatty Acids; D006023:Glycoproteins; D007071:Immunoglobulin A, Secretory; D011506:Proteins; D012709:Serum Albumin