Elastic incoherent neutron scattering as a probe of high pressure induced changes in protein flexibility.

We report here the results of elastic incoherent neutron scattering experiments on three globular proteins (trypsin, lysozyme and beta-lactoglobulin) in different pressure intervals ranging from 1 bar to 5.5 kbar. A decrease of the mean square hydrogen fluctuations, u(2), has been observed upon increasing pressure. Trypsin and beta-lactoglobulin behave similarly while lysozyme shows much larger changes in u(2). This can be related to different steps in the denaturing processes and to the high propensity of lysozyme to form amyloids. Elastic incoherent neutron scattering has proven to be an effective microscopic technique for the investigation of pressure induced changes in protein flexibility.