Accessibility of amino groups in gluten proteins studied by a combination of chemical labeling and immunochemical detection

The accessibility of primary amino groups to an external probe in durum wheat gluten proteins in the flour itself, and after the extraction and separation of gluten proteins, was studied by labeling the free amino groups with the hemisuccinate of 2-(2,4-dichlorophenyl)-3-(1H-1,2,4-triazol-1-yl) propanol (FF18) and evidencing the label immunochemically. Within the flour, the amino groups were less available to the probe than after extraction, and gliadins were less accessible than glutenins, differences that decrease after solubilization and separation of the proteins. Data are discussed in relation to the structural organization of proteins within gluten.