title: Nitrogenase from Klebsiella pneumoniae. An e.p.r. signal observed during enzyme turnover under ethylene is associated with the iron-molybdenum cofactor.
abstract: During turnover at 10 degrees C at pH 7.4 in the presence of ethylene, the MoFe protein of Klebsiella pneumoniae nitrogenase (Kp 1) exhibited an electron-paramagnetic-resonance signal with g-values at 2.12, 1.998 and 1.987. 57Fe isotopic substitution demonstrated that this signal arose from the Kp 1 FeMo-cofactor in an S = 1/2 spin state.
mesh_terms: D003067:Coenzymes / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D005030:Ethylenes; D005288:Ferredoxins / Q000378:metabolism*; D007711:Klebsiella pneumoniae / Q000201:enzymology*; D008983:Molybdoferredoxin / Q000378:metabolism*; D009591:Nitrogenase / Q000378:metabolism*
chemical_list: D003067:Coenzymes; D005030:Ethylenes; D005288:Ferredoxins; D008983:Molybdoferredoxin; C036216:ethylene; D009591:Nitrogenase