Small Angle X-Ray Scattering Spectroscopy
Conformational changes imposed upon the Fe protein during binding and hydrolysis of Mg·ATP are key to initiating the cycle of interactions within the nitrogenase complex that result in gated electron transfer and the eventual multiple electron reduction of dinitrogen to ammonia. Wonderful insights into how nitrogenase accomplishes this have been gleaned from a number of very nice crystal structures, but conformational changes can only be inferred in a very superficial manner, and a number of key conformations relevant to fully understanding conformational changes have eluded this approach. Alternatively, small angle x-ray scattering (SAXS) has proven to be a helpful method for complimenting x-ray crystallography and determining solution structures of various nucleotide-bound states.
Key wordsNitrogenase complex structure conformation SAXS
Portions of the research carried out used to develop the protocols described in this chapter were conducted out at the Stanford Synchrotron Radiation Laboratory, a national user facility operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences. The SSRL Structural Molecular Biology Program is supported by the Department of Energy, Office of Biological and Environmental Research and by the National Institutes of Health, National Center for Research Resources, Biomedical Technology Program, and the National Institute of General Medical Sciences.
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