Proton mobilities in crambin and glutathione S-transferase

Using a neutron backscattering spectrometer, the temperature dependence of mean-square atomic displacements derived from window-integrated quasielastic spectra was measured for two D2O-hydrated proteins: crambin and glutathione S-transferase. Analyses show that the anharmonic dynamics observed around and above 200 K is consistent with a description in terms of proton/deuteron jumps within asymmetric double-minimum potentials. Also determined were activation energies along with estimates of effective masses and average oscillator energies