Prolamines

Prolamines are a class of plant seed storage proteins characterized by a high content of the amino acids proline and glutamine and by their distinctive solubility properties. They are soluble in 60-80% aqueous ethanol and largely insoluble in water, accumulating in cereal seeds as a reserve for germination.

Different cereals have different prolamins: in wheat they are gliadins, in rye secalins, in barley hordeins, in maize zeins, and in oats avenins. Prolamins are often low in lysine and sulfur-containing amino acids and lack extensive disulfide cross-linking, which distinguishes them from the related glutelins. They are typically rich in repetitive sequences of proline and glutamine.

In wheat, prolamins interact with glutelins to form the gluten network that gives dough its viscoelastic properties; however, prolamins themselves are usually monomeric or form limited polymers.

Some prolamins, particularly gliadins, contain epitopes that can trigger autoimmune responses in individuals with genetic susceptibility, leading to celiac disease; other cereals have similar but distinct epitopes. The health relevance of prolamines varies among individuals and cereals, and oats, for example, contain avenins that are generally tolerated by many with celiac disease but may still pose a risk in some cases.

Because of their role in gluten, prolamines are central to nutrition, allergen labeling, and gluten-free product development. Methods for detecting prolamins focus on species-specific assays and peptide epitopes.