[1] Inst Pasteur, Unite Resonance Magnet Nucl Biomol, Dept Biol Struct & Chim, F-75724 Paris 15, France
[2] Univ Paris 06, Cellule Pasteur UPMC, Paris, France
[3] Inst Pasteur, Plate Forme Biophys Macromol, F-75724 Paris 15, France
[4] Saclay, Lab Biol Struct & Radiobiol, Gif Sur Yvette, France
[5] Soleil Synchrotron, Orme Merisiers St Aubin, Gif Sur Yvette, France
[6] Inst Pasteur, F-75724 Paris 15, France