Viscoelastic properties of wheat gluten in a molecular dynamics study

Abstract

Wheat (Triticum spp.) gluten consists mainly of intrinsincally disordered storage proteins (glutenins and gliadins) that can form megadalton-sized networks. These networks are responsible for the unique viscoelastic properties of wheat dough and affect the quality of bread. These properties have not yet been studied by molecular level simulations. Here, we use a newly developed α-C-based coarse-grained model to study ∼ 4000-residue systems. The corresponding time-dependent properties are studied through shear and axial deformations. We measure the response force to the deformation, the number of entanglements and cavities, the size of fluctuations, the number of the inter-chain bonds, etc. Glutenins are shown to influence the mechanics of gluten much more than gliadins. Our simulations are consistent with the existing ideas about gluten elasticity and emphasize the role of entanglements and hydrogen bonding. We also demonstrate that the storage proteins in maize and rice lead to weaker elasticity which points to the unique properties of wheat gluten.

Gluten Adhesion and Shearing in a Contact-Based Coarse-Grained Model

“…The simulation protocol and the general properties of gluten are discussed in Ref. [3]. Here we summarize only the most important information about the simulated systems.…”

“…The average number of residues in gliadins is 290. Glutenins are longer, with an average length of 445 residues [3]. The total number of residues in the gluten system studied is 4271.…”

“…Periodic oscillations (O) are reflected in the oscillating n c (especially for adaptive walls in pull mode). It is interesting to note that the final pulling (P) does not lead to a large decrease in n c , because inter-chain contacts are replaced by intra-chain contacts [3].…”

“…Another property that changes with n c is the critical strain: for higher strains the sample is torn apart. This is realized in our simulations by recording the distance s max between the walls, for which the highest maximum in the force occurs during pulling apart the walls [3]. The distance in equilibrium is s 0 , so critical strain = (s max − s 0 )∕s 0 .…”

“…It is mostly an ensemble of proteins that are intrinsically disordered. We have recently proposed a protocol to study viscoelasticity of such ensembles through molecular dynamics simulations [3]. The protocol uses our novel coarse-grained model [4] that has been designed primarily for the intrinsically disordered proteins.…”