IDENTIFICATION OF MAJOR RYE SECALINS AS CELIAC IMMUNOREACTIVE PROTEINS

Six distinct gamma- and omega-type secalins, together with two new low molecular mass glycoproteins, have been identified as the major coeli ac immunoreactive proteins from a chloroform/methanol soluble extract from rye endosperm. These components were characterized by a combinati on of reverse-phase high-performance liquid chromatography, immunoblot ting using a coeliac serum and microsequencing analysis. This allowed the identification of a group of secalins with different molecular mas ses according to their N-terminal amino-acid sequence: one omega-type secalin of 40 kDa (omega 1-40); three gamma-type secalins, one of 70 k Da (gamma-70) and two of 35 kDa (gamma-35); as well as two low molecul ar mass glycoproteins of 15 and 18 kDa, all exhibiting coeliac serum a ntigenicity. Moreover, four additional rye components, including two l ow molecular mass proteins, which did not react with coeliac sera, hav e also been identified. Analysis by matrix-assisted laser desorption/i onization time-of-flight mass spectrometry (MALDI-TOF MS) of the three main purified coeliac immunogenic secalins, gamma-70, gamma-35 and om ega 1-40, indicated molecular masses of 71457, 32240 and 39117 Da, res pectively. The omega 1-40 secalin displays a significant absorption in the visible region which could be related to its peculiar low capacit y to bind both coeliac sera antibodies and Coomassie brilliant blue dy e.