Digestibility and immunoreactivity of soybean β-conglycinin and its deglycosylated form

IgE-mediated allergy to soybean may be connected to an incomplete protein digestion causing an inappropriate immune response in the gut. The aim of this study was to gain insight on the digestibility and immunoreactivity of beta-conglycinin and its deglycosylated form. To achieve this goal both proteins were digested mimicking gastrointestinal physiological conditions. Digests were characterised by SDS-PAGE, MALDI-TOF-MS and immunological assays. Data on IgG binding western blot provided key information related to the composition of the digests indicating that whereas deglycosylated beta-conglycinin was completely removed by gastrointestinal digestion, alpha and beta subunits of beta-conglycinin glycoprotein partially survive the process of digestion. Such differential digestive behaviour might be influenced by glycan moieties, at least to some extent, and should be an additional factor to be considered on its potential allergenicity. Results also support the existence of linear epitopes in the three subunits (alpha, alpha', and beta) of both protein forms. (C) 2011 Elsevier Ltd. All rights reserved.