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Conformational Ensembles from Experimental Data
and Computer Simulations
Poster Abstracts
98
63-POS
Board 23
Lukasz Mioduszewski
, Marek Cieplak.
Polish Academy of Sciences, Warsaw, Poland.
Gluten proteins do not seem to have one clearly defined tertiary structure, and can form
covalently and non-covalently joined megadalton-sized complexes. They form a
mechanochemical network, responsible for the viscoelastic properties of wheat dough. The
properties can be characterized by the dynamic Young modulus G* = G' + G′′, which describes
the response to small-amplitude oscillating deformation: G′ for the in-phase (elastic) part and G′′
for the out-of-phase (viscous) part. The main goal of this work is to present a model that can
recreate this elastic response of gluten in computer simulations. The existing theories of gluten
elasticity point out the crucial role of hydrogen and disulfide bonds between different gluten
protein chains. The theories provide some predictions that can be incorporated into a simple
coarse-grained model of gluten. In the model amino acids are represented as pseudoatoms,
connected harmonically to form protein chains. Non-bonded interactions include Lenard-Jones
potential, which mimics hydrogen bonding, and a dynamic potential for disulfide bonds. Initial
chain conformations are generated randomly, and then evolve according to the simplified
potential, forming large complexes. The results were obtained by periodically deforming the box
containing gluten proteins and recording the response force. The amplitude of the response force
seems to increase, indicating strain hardening, an effect observed in experiments. It is
accompanied by changes in the protein network structure: the number of inter-chain hydrogen
and disulfide bonds increases. The connection between those conformational changes and system
response to deformation is discussed, as well as the ability of simple models to predict properties
of large complexes of disordered proteins.