title: Iron K-edge X-ray absorption spectroscopy of the iron-molybdenum cofactor of nitrogenase from Klebsiella pneumoniae.
abstract: Iron K-edge X-ray absorption data for the iron-molybdenum cofactor ('FeMoco') from Klebsiella pneumoniae reported here provide the first evidence for long-range structural order in the cofactor [Fe...Fe(Mo) = 0.368 nm in addition to Fe...S = 0.22 nm and Fe...Fe(Mo) = 0.27 nm] and, in contrast with previously published data [Antonio, Teo, Orme-Johnson, Nelson, Groh, Lindahl, Kauzlarich & Averill (1982) J. Am. Chem. Soc. 104, 4703-4705], indicate that most of the iron centres are not co-ordinated to light (oxygen, nitrogen) atoms. This demonstrates that presently available chemical models for FeMoco are inadequate.
mesh_terms: D005288:Ferredoxins / Q000032:analysis*; D007501:Iron / Q000032:analysis*; D007711:Klebsiella pneumoniae / Q000201:enzymology*; D008983:Molybdoferredoxin / Q000032:analysis*; D009591:Nitrogenase; D013057:Spectrum Analysis; D014965:X-Rays
chemical_list: D005288:Ferredoxins; D008983:Molybdoferredoxin; D007501:Iron; D009591:Nitrogenase