Identification of the three major coeliac immunoreactive proteins and one alpha-amylase inhibitor from oat endosperm.

Six chloroform/methanol-soluble proteins from oat endosperm (Avena sativa) have been isolated and characterized by a purification procedure based on extraction with volatile solvents, followed by reversed-phase high performance liquid chromatography. Three of these proteins, with an assessed molecular weight of 25,000, 27,000 and 32,000 Da, respectively, have been identified by immunoblotting using coeliac sera, as the major coeliac serum IgA-binding components of oat endosperm. The N-terminal amino acid sequence of these proteins indicates that they correspond to alpha 2, gamma 4, and gamma 3 avenins, respectively. We have tentatively named them 'coeliac immunoreactive proteins'. Another chloroform/methanol oat component shows weak alpha-amylase inhibitory activity and exhibits strong homology (60% identity) at the N-terminus with the alpha-amylase inhibitor from ragi (Eleusine coracana).