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The interaction between proteins and hydration water stabilizes protein structure and promotes functional dynamics, with hydration water enabling protein flexibility. However, some engineered solvent-free protein-polymer hybrids have been shown to preserve protein structure, function and dynamics [1,2]. Here we have studied the dynamics of myoglobin conjugated with a polymer surfactant corona. We performed elastic, quasi-elastic and inelastic neutron scattering at ILL (Grenoble) and MLZ (Garching) to probe dynamics of the protein-polymer hybrid on the ns-ps timescale. In addition, we combined the measurements with MD simulations to gain molecular insights into the molecular motions and verify the relevance of the model used to treat scattering data. After validating the simulations by computing the neutron scattering functions directly from the trajectories, we analyzed hydrogen bond dynamics, mean-square displacements and displacement densities. Both polymer and protein scattering data, measured between 200 and 300 K, have been interpreted using a two-well model, which highlighted coupled motions above the dynamical transition. Further analysis of the MD simulations indicated diffusive-like motions in the polymer and confined motions in the protein [3]. Based on these results, we postulate that liquid-like polymer dynamics plasticize the conjugated protein in a qualitatively similar way as do hydration-water translational motions.
(1) Perriman, A. W.; Brogan, A. P. S.; Cölfen, H.; Tsoureas, N.; Owen, G. R.; Mann, S. Reversible Dioxygen Binding in Solvent-Free Liquid Myoglobin. Nat. Chem. 2010, 2 (8), 622–626.
(2) Gallat, F.-X.; Brogan, A. P. S.; Fichou, Y.; McGrath, N.; Moulin, M.; Härtlein, M.; Combet, J.; Wuttke, J.; Mann, S.; Zaccai, G.; Jackson, C. J.; Perriman, A. W.; Weik, M. A Polymer Surfactant Corona Dynamically Replaces Water in Solvent-Free Protein Liquids and Ensures Macromolecular Flexibility and Activity. J. Am. Chem. Soc. 2012, 134 (32), 13168–13171.
(3) Schirò G, Fichou Y. , Brogan A.P.S., Sessions R., Lohstroh W., Zamponi M., Schneider G.J., Gallat F.X., Paciaroni A., Tobias D.J., Perriman A., Weik M. Diffusive-like motions in a solvent free protein-polymer hybrid, under review.
| Scientist Profile | None of the above, but I am under 35 years old |
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