Evans G, Wilson K S
European Molecular Biology Laboratory (EMBL) Hamburg, c/o DESY, Notkestrasse 85, 22603 Hamburg, Germany and Department of Physics, University of Warwick, Coventry CV4 7AL, England.
Acta Crystallogr D Biol Crystallogr. 1999 Jan;55(Pt 1):67-76. doi: 10.1107/S090744499800732X. Epub 1999 Jan 1.
A multiple-wavelength anomalous diffraction (MAD) experiment was performed on an iridium derivative of hen egg-white lysozyme. Diffraction data were measured at five wavelengths on the X31 EMBL beamline on the DORIS III storage ring and at two further wavelengths on the X11 beamline. Four iridium-binding sites were located from the dispersive anomalous differences between two wavelengths at the rising and falling inflection points of the Ir LIII-edge white line using direct methods. All other attempts to determine the heavy-atom positions failed. The results demonstrate an experimental method whereby systematic error in MAD data due to sample absorption can be reduced where a white line is present in the absorption spectrum of a heavy atom.
对鸡蛋清溶菌酶的铱衍生物进行了多波长反常衍射（MAD）实验。在DORIS III储存环的X31 EMBL光束线上于五个波长处以及在X11光束线上于另外两个波长处测量了衍射数据。利用直接法，从Ir LIII边白线的上升和下降拐点处两个波长之间的色散反常差异中确定了四个铱结合位点。所有其他确定重原子位置的尝试均告失败。结果证明了一种实验方法，即在重原子的吸收光谱中存在白线的情况下，可减少MAD数据中由于样品吸收导致的系统误差。
