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.