Isolation and fractionation of human gastric mucus gel

A high yield method for collecting mucus from resection stomach specimens was developed. Lyophilized samples of mucus were totally fractionated by stepwise extraction in three different solvents: 0.2 M Tris-HCl buffer, pH 8.0, 1% SDS solution in the same buffer and 0.2 M 2-mercaptoethanol solution in a Tris-HCl-1% SDS buffer. The fractions obtained were submitted to gel filtration, SDS-polyacrylamide-agarose gel electrophoresis and analyzed for their protein and glycoprotein components. All fractions differed in their carbohydrate-to-protein ratio and after reduction with 2-mercaptoethanol in the presence of SDS, released a substantial amount of low molecular weight components. A high molecular weight glycoprotein was present in all the fractions, which could be split into glycoprotein subunits with 2-mercaptoethanol in dissociating conditions only. The properties of the human gastric mucus as demonstrated in these studies differ in some respects from the pig and suggest its more complicated nature.