The toxic fraction of gliadin digests in coeliac disease. Isolation by chromatography on Biogel P-10

Improvement in the fractionation of gliadin digests and in the isolation of toxic fractions was achieved using chromatography on Biogel P-10. Fraction V, one of the 11 fractions eluted from a peptic-tryptic digest of crude gliadin extracted from Cappelle wheat, significantly affected coeliac jejunal mucosa in organ culture. BV, gamma V, omega V, the corresponding fractions V from beta-, gamma- and omega-gliadins, displayed similar toxic effects. Fraction VI containing peptides with a lower molecular mass did not show any significant cytotoxic activity and, moreover, inhibited the toxicity of fraction V. Analysis of the toxic fractions V showed that they contained peptides of 7-8,000 molecular mass, rich in proline and glutamine and poor in aromatic amino acids and carbohydrates. Among the various fractions, V, beta V from beta-gliadin appeared the less heterogeneous.