Amylopectin sulphate (SN-263) coats the gastric mucosal surface.

After the application in vitro of (14)C amylopectin sulphate solution to frozen sections of human ulcer-bearing stomach, autoradiography demonstrates localization of amylopectin sulphate to the gastric surface. The affinity of amylopectin sulphate macromolecule for the gastric luminal surface would provide a substrate-bound pepsin inhibitor with a molecular sieve-like action to exclude proteolytic enzymes from the mucosal surface. This protective coating action may mimic the hypothetical role of endogenous gastric mucous substances and account for the action of amylopectin sulphate in human peptic ulcer.