LC/MS ANALYSIS OF GLUTEN PEPTIDES DERIVED FROM SIMULATED GASTROINTESTINAL DIGESTION OF DIFFERENT WHEAT VARIETIES: QUALITY AND SAFETY IMPLICATIONS. Sforza, Stefano & Prandi, Barbara & Bencivenni, Mariangela & Tedeschi, Tullia & Dossena, Arnaldo & Marchelli, Rosangela & Galaverna, Gianni. (2011):
Abstract:
“Gluten content of wheat is highly variable, depending on the plant genetics and the growing conditions. Beside short peptides, gastrointestinal digestion of gluten also produces longer ones, since the high proline content of gliadins (16-26%) and glutenins (11-13%) makes them very resistant to the degradation by digestive proteases. In the present work, a method for the extraction of the prolamine fraction was applied to different wheat varieties, followed by a simulated gastrointestinal digestion of the gliadin extracted. The peptide mixtures generated were characterized by LC/MS, and most abundant peptides were identified by low- and high-resolution multiple stage MS techniques and through synthesis of authentic standards. These peptides were also semiquantified in the different samples against a suitable internal standard. The peptide mixtures were found to be highly variable, according to the different content and type of gliadins present in wheat varieties, with strong differences among the varieties tested, both qualitatively (the sequences of the peptides generated) and quantitatively (their amount). The greatest difference was found between common and durum wheat varieties. Peptides present only in the former varieties were identified, and used as molecular markers for identifying and quantifying the presence of common wheat when added to durum wheat samples. Most of the peptides identified were also already known to be pathogenic for people affected by celiac disease, an autoimmune enteropathy triggered by gluten proteins, which develops in some genetically susceptible subjects after gluten consumption. Some samples belonging to defined varieties showed a lower amount of celiac-related pathogenic peptides upon digestion, due to a lower gliadin content. Albeit not safe for celiac patients, the use of these varieties in the formulations of baby food could be of great help for lowering the spread of the disease, since the prevalence of celiac disease seems to be promoted by an early exposure to a large amount of gluten peptides”.