Comparative investigations of gluten proteins from different wheat species. III. N-terminal amino acid sequences of alpha-gliadins potentially toxic for coeliac patients

Studies on the coeliac toxicity of wheat have been focused on common (bread ) wheat. Other cultivated wheat species were tested in an inadequate manner or were tested not at all. Because in vivo testing by feeding to coeliac p atients is out of the question for ethical reasons, the different species w ere compared by N-terminal sequences of alpha -gliadins including the poten tial toxic sequences. Flours of durum wheat, emmer, and einkorn were succes sively extracted with a salt solution and 60% ethanol. The alcoholic extrac ts (gliadins) were preparatively separated by reversed-phase HPLC using an elution system optimized for alpha -gliadins. Five to six different alpha - gliadin fractions were isolated from each species and were characterized by the determination of N-terminal amino acid sequences. The results for 30 s teps of Edman degradation indicated a high degree of sequence homology with in the N-terminal region and a close relationship with corresponding sequen ces of alpha -gliadin fractions from bread wheat and spelt wheat [12]. The a-gliadins from all wheat species investigated contained amino acid sequenc es potentially activating coeliac disease. For this reason, all cultivated wheat species are assumed to be coeliac toxic cereals and should be avoided by coeliac patients.