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A novel S = 3/2 EPR signal associated with native Fe‐proteins of nitrogenase
Author(s) -
Hagen W.R.,
Eady R.R.,
Dunham W.R.,
Haaker H.
Publication year - 1985
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(85)81033-4
Subject(s) - azotobacter vinelandii , electron paramagnetic resonance , nitrogenase , azotobacter chroococcum , chemistry , azotobacteraceae , excited state , signal (programming language) , nuclear magnetic resonance , ground state , analytical chemistry (journal) , atomic physics , physics , nitrogen fixation , biology , chromatography , organic chemistry , computer science , nitrogen , immunology , inoculation , programming language
In addition to their g = 1.94 EPR signal, nitrogenase Fe‐proteins from Azotobacter vinelandii, Azotobacter chroococcum and Klebsiella pneumoniae exhibit a weak EPR signal with g ≅5. Temperature dependence of the signal was consistent with an S = system with negative zero‐field splitting, d = −5 ± 0.7 cm −1 . The m s , = ± ground state doublet gives rise to a transition with g eff = 5.90 and the transition within the excited m s = ± doublet has a split g eff = 4.8, 3.4. Quantitation gave 0.6 to 0.8 spin mol −1 which summed with the spin intensity of the S = g = 1.94 line to roughly 1 . MgATP and MgADP decreased the intensity of the s = signal with no concomitant changes in intensity of the s = signal.