Of trees, vines, and the jungle: how impervious is the gluten network?

"Nature is immense and complex, but not impervious to intelligence…: we must look for the opening, or make it". This quotation from Primo Levi's "The Periodic Table" applies very fittingly to the many - and still ongoing - attempts at untangling the maze of flexible protein molecules than through a number of distinct and ever-changing interactions make up the gluten network in grains, flours, dough, and in most cereal-based products. The approaches described here rely on specific fluorescent reagents, that have been used to assess the exposure of suitable "reporter" residues under a variety of network-loosening conditions (presence of detergents or chaotropes, for instance). Single- and double-labeling techniques were used to label with distinct fluorophores protein thiols exposed under various conditions, allowing a preliminary proteomics analysis of the mutual relationships among proteins in grains and in foods and – possibly - of their changes upon processing. We will also report on recent developments in attempts at using gold nanoparticles for similar "conditional accessibility" studies, taking advantage of the remarkable thiol reactivity of the surface of these nanoparticles and of the resistance of such an interaction to some of the most popular network-dissociating agents. The nature of the nanoparticle-bound proteins was investigated in the frame of collecting information on "gluten interactomics”, by exploiting the possibility of "pulling" from the gluten network both those proteins that expose gold-reactive residues and those that are interacting with the nanoparticle-captured proteins through either disulfide or non-covalent bonds. Key learning objectives - Methods for assessing reactivity/accessibility of individual proteins in gluten - Exploring protein-protein interactions in gluten - Potential uses of nanoparticles in cereal protein chemistry