Glycosulfatase Activity of H. pylori toward Human Gastric Mucin: Effect of Sucralfate

Colonization of gastric mucosa by Helicobacter pylori, a bacterium implicated in the etiology of gastric disease, involves the cell surface sulfated glycosphin‐golipid receptors for the attachment. Evidence has also been obtained recently that sulfated mucus glycoproteins have the ability to interfere with this process. Here, we show that H. pylori displays glycosulfatase activity, and report the specificity of this enzyme toward gastric mucosal sulfated glycoproteins and glycolipids. With ³⁵S‐labeled human gastric sulfated mucin as substrate, the enzyme activity was identified in the extracellular material elaborated by the bacterium. The glycosulfatase exhibited maximum activity at pH 5.7 in the presence of Triton X‐100 and CaCl₂, and gave on SDS‐PAGE a protein band of 30 kDa. Specificity studies revealed that the enzyme effectively caused desulfation of N‐acetylglucosamine‐6‐sulfate and galactose‐6‐sulfate present in carbohydrate chains of gastric mucins, as well as that of glucose‐6‐sulfate, a constituent of mucus glyceroglucolipids. However, the H. pylori glycosulfatase was ineffective toward galactosyl‐ and lactosylceramide sulfates which serve as receptors for this bacterium attachment and contain the sulfate ester group at C‐3 of galactose. The glycosulfatase activity toward human sulfated gastric mucin was inhibited by sucralfate. The inhibitory effect was proportional to the concentration of sucralfate up to 120 μg/ml, at which a 78% decrease in mucin desulfation occurred. The results demonstrate that H. pylori, through its glycosulfatase activity, affects the sulfated mucin and glyceroglucolipid content of the protective mucus layer, and that antiulcer drug sucralfate is able to counteract the detrimental action of this enzyme.