Proton and deuteron relaxation study of molecular dynamics in lysozyme solutions

A nuclear magnetic resonance spin-lattice relaxation dispersion study of th e relaxation of several magnetization components in both natural and deuter ated lysozyme solutions was undertaken at 20 degrees C. Proton and deuteron resonances were employed. The two-dimensional time evolution of the magnet ization and the spin-spin relaxation were analyzed. In addition, an isotopi c dilution study was performed at 5 and 30.6 MHz. The results indicate that the water proton spin-lattice relaxation rate which arises from intermolec ular relaxation between the water protons and the lysozyme protons represen ts a relatively strong relaxation mechanism. A model for the dynamics of th e water molecules, consistent with the proton and deuteron dispersions as w ell as with the isotopic dilution results, is presented.