%0 journal article %@ 0909-0495 %A Boesecke, P., Bois, J.M., Crepin, T., Hunte, C., Kahn, R., Kao, W.-C., Nauton, L., Winther, A.-M.L., Moller, J., Nissen, P., Nury, H., Olesen, C., Pebay-Peyroula, E., Vicat, J., Stuhrmann, H.B. %D 2009 %J Journal of Synchrotron Radiation %N 5 %P 658-665 %R doi:10.1107/S0909049509025692 %T A first low-resolution difference Fourier map of phosphorus in a membrane protein from near-edge anomalous diffraction %U https://doi.org/10.1107/S0909049509025692 5 %X Crystal diffraction of three membrane proteins (cytochrome bc1 complex, sarcoplasmic reticulum Ca2+ ATPase, ADP-ATP carrier) and of one nucleoprotein complex (leucyl tRNA synthetase bound to tRNAleu, leuRS:tRNAleu) was tested at wavelengths near the X-ray K-absorption edge of phosphorus using a new set-up for soft X-ray diffraction at the beamline ID01 of the ESRF. The best result was obtained from crystals of Ca2+ ATPase [adenosin-5'-([beta],[gamma]-methylene) triphosphate complex] which diffracted out to 7 Å resolution. Data were recorded at a wavelength at which the real resonant scattering factor of phosphorus reaches the extreme value of -20 electron units. The positions of the four triphosphates of the monoclinic unit cell of the ATPase have been obtained from a difference Fourier synthesis based on a limited set of anomalous diffraction data.