Magnetization transfer from laser-polarized xenon to protons located in the hydrophobic cavity of the wheat nonspecific lipid transfer protein

Nonspecific lipid transfer protein from wheat is studied by liquid-state NM R in the presence of xenon. The gas-protein interaction is indicated by the dependence of the protein proton chemical shifts on the xenon pressure and formally confirmed by the first observation of magnetization transfer from laser-polarized xenon to the protein protons. Twenty-six heteronuclear nOe s have allowed the characterization of four interaction sites inside the wh eat ns-LTP cavity, Their locations are in agreement with the variations of the chemical shifts under xenon pressure and with solvation simulations. Th e richness of the information obtained by the noble gas with a nuclear pola rization multiplied by similar to 12,000 makes this approach based on dipol ar cross-relaxation with laser-polarized xenon promising for probing protei n hydrophobic pockets at ambient pressure.