Coeliac Disease. V. Some Experiments on the Cause of the Harmful Effect of Wheat Gliadin

Abstract

In previous studies it was demonstrated that a protein fraction of wheat, gliadin, is associated with the production of symptoms in the majority of patients with coeliac disease. The present paper describes further efforts to determine the manner in which this substance exerts its harmful effects. The experiments indicate that the harmful effects of gliadin are destroyed if it is boiled with IN hydrochloric acid for a brief period. Gliadin contains 43 per cent glutamine and the effect of the acid treatment is to convert the glutamine into glutamic acid. The author proposes the hypothesis that glutamine, bound in gliadin—but not the free amino acid glutamine—is responsible for the harmful effects of wheat protein upon coeliac disease. The ratio of amid-nitrogen to non-amid-nitrogen in different foodstuffs was determined. All the protein foods which have been found to be harmful have values for this ratio higher than 11; gluten and gliaden have especially high values, 27 and 30, respectively.