Gliadinen

Gliadin, also referred to as gliadinen in some languages, is a class of storage proteins found in the seeds of wheat and related cereals. It is one of the two major components of gluten, the other being glutenin. Together, gliadins and glutenins form a viscoelastic network in dough that contributes to its extensibility and strength, characteristics essential for bread-making.

Gliadins are alcohol-soluble prolamins that are rich in the amino acids proline and glutamine. They occur as several isoforms, traditionally classified into four groups: alpha-, beta-, gamma-, and omega-gliadins. These proteins are encoded by multigene families and accumulate in the endosperm during grain development. The high proline and glutamine content makes gliadins resistant to complete digestion, yielding peptide fragments that can interact with the immune system.

Clinical relevance is most often discussed in the context of celiac disease. In genetically predisposed individuals, certain gliadin-derived peptides trigger autoimmune responses after modification by tissue transglutaminase, increasing their affinity for HLA-DQ2 or HLA-DQ8 molecules and promoting intestinal inflammation. Gliadins can also act as allergens in wheat allergy, though celiac disease involves a specific immune reaction to gliadin peptides.

Gluten-containing cereals include wheat, barley, and rye, which harbor related prolamins (gliadins in wheat, secalins in rye, and hordeins in barley). Understanding the structure and immunogenic epitopes of gliadins informs dietary management of gluten-related disorders and breeding efforts aimed at reducing immunogenicity.