Combining structure and dynamics: non-denaturing high-pressure effect on lysozyme in solution

Résumé: Small-angle X-ray scattering (SAXS), elastic and quasi-elastic neutron scattering techniques were used to investigate high-pressure-induced changes on interactions, low-resolution structure and dynamics of lysozyme in solution. SAXS data indicate that lysozyme completely maintains its globular structure up to 1500 bar, but significant modifications in the protein–protein interaction potential occur at approximately 600–1000 bar. Moreover, the mass density of the protein hydration water shows a clear discontinuity within this pressure range. Neutron scattering experiments indicate that the global and the local lysozyme dynamics change at a similar threshold pressure. A clear evolution of the internal protein dynamics from diffusing to more localized motions has also been probed. Protein structure and dynamics results have then been discussed in the context of protein–water interface and hydration water dynamics. According to SAXS results, the new configuration of water in the first hydration layer induced by pressure is suggested to be at the origin of the observed local mobility changes