Redox properties and electron paramagnetic resonance spectroscopy of the transition state complex of Azotobacter vinelandii nitrogenase

FEBS Letters

Arendsen, A.F.¹  Marritt, S.J.¹  Wassink, H.¹  Haaker, H.¹  Hagen, W.R.¹  Spee, J.H.¹ 

[1] Laboratory of Biochemistry, Department of Biomolecular Sciences, Agricultural University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands

关键词: Nitrogenase (Azotobacter vinelandii);    Transition state complex;    Redox potential;    Electron paramagnetic resonance;    MoFe protein;    molybdenum-iron protein of nitrogenase;    Fe protein;    iron protein of nitrogenase;    FeMoco;    the iron-molybdenum-sulfur-homocitrate cofactor of nitrogenase;    FeMocoN;    FeMocosuper red;    FeMocoox;    the dithionite reduced;    super-reduced and one electron oxidized FeMoco;    P-cluster;    the [8Fe-7S] cluster of nitrogenase;    PN;    Psemi ox;    Pox;    the dithionite reduced;    one- and two-electron oxidized P-cluster;    NHE;    normal hydrogen electrode;    AlF;    all forms of aluminum(III) with an F−;    H2O and OH− coordination;   

DOI  :  10.1016/S0014-5793(98)00827-8

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Nitrogenase is a two-component metalloenzyme that catalyzes a MgATP hydrolysis driven reduction of substrates. Aluminum fluoride plus MgADP inhibits nitrogenase by stabilizing an intermediate of the on-enzyme MgATP hydrolysis reaction. We report here the redox properties and electron paramagnetic resonance (EPR) signals of the aluminum fluoride-MgADP stabilized nitrogenase complex of Azotobacter vinelandii. Complex formation lowers the midpoint potential of the [4Fe-4S] cluster in the Fe protein. Also, the two-electron reaction of the unique [8Fe-7S] cluster in the MoFe protein is split in two one-electron reactions both with lower midpoint potentials. Furthermore, a change in spin-state of the two-electron oxidized [8Fe-7S] cluster is observed. The implications of these findings for the mechanism of MgATP hydrolysis driven electron transport within the nitrogenase protein complex are discussed.

【 授权许可】

Unknown