Prolamin storage proteins are the main repository for nitrogen in the endosperm of cereal seeds. These stable proteins accumulate at massive levels due to the high-level expression from extensively duplicated genes in endoreduplicated cells.
Prolamins contain large amounts of the amino acids proline and glutamine (from which the name prolamin is derived) but only small amounts of arginine, lysine, and histidine. These proteins are characterized by having a-helix globular domain with 6-8 cysteine residues and 3-4 disulfide bonds being highly soluble in ethanol (40-70%).
Prolamins are a key determinant of hard kernel texture in the mature seed; an essential characteristic of cereal grains like maize. However, deficiencies of key essential amino acids in prolamins result in relatively poor grain protein quality.
The prolamins of wheat, barley, and rye are divided into sulfur-rich (α-, β- γ gliadins), sulfur-poor (ω-gliadins), and high-molecular-weight proteins. On the other hand, they get their names from the cereal source they are extracted from, for example: secalin (rye), hordein (barley), avenin (oats), zein (corn), orzein (rice), kafirin (sorghum) and gliadin (wheat).
The prolamin protein fractions of wheat and related grains are implicated in the causation of celiac disease. The prolamin fraction of wheat is known as gluten, so celiac disease is sometimes referred to as gluten-sensitive enteropathy.
What is prolamin?
