To assess changes in the antigenicity of gliadin during proteolysis, t
wo model systems of hydrolysis using pepsin or trypsin in the presence
of urea or dioxan were tested. Rabbit polyclonal antibodies against w
hole gliadin were used in two ELISA procedures. The first one involved
direct analysis of antigliadin antibody binding. The second one used
anti-immunoglobulin Ci antibodies to indirectly test the antigliadin a
ntibodies reacting with hydrolysis products. The antigenicity of pepsi
n-hydrolysed gliadin decreased only slowly during hydrolysis and was m
aintained at about 45% of the initial value for up to 24 h. Qualitativ
ely, after 3 h of hydrolysis, antigenic reactivity pattern seemed to r
eveal some marked conformational changes. Tryptic hydrolysis failed to
modify significantly the antigenicity in either denaturing agent (ure
a or dioxan).