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Center for Nonlinear Studies |
In this presentation we show that a simple model for the QENS spectra of proteins enables the detection of small but systematic changes in the dynamics of human Acetylcholinesterase upon non-covalent binding of a Huperzine A ligand. The model describes the diffusion of the Fourier-transformed single particle density in an effective ‘rough’ harmonic potential. The fit parameters are the elastic scattering amplitude and two parameters describing the asymptotic power law relaxation of the intermediate scattering function. The spectral analysis is carried out in both time and frequency domain. In the first case, the model intermediate scattering function is fitted to the experimental data after instrumental deconvolution of the Fourier transformed spectra and in the second case the measured spectra are fitted with a semi-analytical convolution of the model dynamic structure factor with the instrumental resolution function. Both analyses indicate the same dynamical changes, which can be resumed by a slight softening and roughening of the effective potential.
[1] G. R. Kneller, “Franck–Condon picture of incoherent neutron scattering”, PNAS USA, vol. 115, no. 38, pp. 9450–9455, 2018. [2] M. Saouessi, J. Peters, and G. R. Kneller, “Asymptotic analysis of quasielastic neutron scattering data from human acetylcholinesterase reveals subtle dynamical changes upon ligand binding,” J. Chem. Phys., vol. 150, pp. 161104-9, 2019. [3] M. Saouessi, J. Peters, and G. R. Kneller, “Semi-analytical approach to frequency domain modeling of quasielastic neutron scattering from proteins : Application to free and inhibited Acetylcholinesterase”, manuscript in preparation
Host: Paul Fenimore