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Novel EPR signals associated with FeMoco centres of MoFe protein in MgADP‐inhibited turnover of nitrogenase
Author(s) -
Maritano Silvana,
Fairhurst Shirley A,
Eady Robert R
Publication year - 2001
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/s0014-5793(01)02800-9
Subject(s) - electron paramagnetic resonance , nitrogenase , dithionite , chemistry , enzyme , crystallography , biochemistry , stereochemistry , nuclear magnetic resonance , nitrogen fixation , physics , organic chemistry , nitrogen
Two novel electron paramagnetic resonance (EPR) signals arising from the [1Mo–7Fe–9S‐homocitrate] (FeMoco) centres of MoFe protein of Klebsiella pneumoniae nitrogenase (Kp1) were observed following turnover under MgATP‐limited conditions. The combination of the nitrogenase Fe protein of Clostridium pasteurianum showed similar signals. The accumulation of MgADP under these conditions causes the normal EPR signal of dithionite‐reduced Kp1 (with g =4.3, 3.6, 2.01) to be slowly converted to novel signals with g =4.74, 3.32, 2.00 and g =4.58, 3.50, 1.99. These signals do not form in incubation of protein mixtures containing only MgADP, thus they may be associated with trapped intermediates of the catalytic cycle.