Open AccessProton Magnetic Resonance and Magnetic Susceptibility Characterization of Ferredoxin I from Bacillus polymyxa
Author(s) -
William D. Phillips,
C. C. McDonald,
N.A. Stombaugh,
William H. OrmeJohnson
Publication year - 1974
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.71.1.140
Subject(s) - ferredoxin , chemistry , intramolecular force , resonance (particle physics) , redox , nuclear magnetic resonance , proton , electron transfer , electron paramagnetic resonance , magnetic susceptibility , crystallography , photochemistry , stereochemistry , physics , inorganic chemistry , biochemistry , atomic physics , enzyme , quantum mechanics
Magnetic susceptibility and proton magnetic resonance spectra are reported for the oxidized and reduced forms of the iron-sulfur proteinBacillus polymyxa ferredoxin I. The magnetic susceptibility of the oxidized form indicates antiferromagnetic exchange coupling between component iron atoms that is quantitatively similar to that observed for the clostridial ferredoxins and for the [(C2 H5 )4 N]2 [Fe4 S4 (SCH2 C6 H5 )4 ] analog. Contact-shifted resonances observed in the proton-magnetic-resonance spectra of oxidized and reduced forms of theB. polymyxa protein can be correlated with the contact-shifted resonances of corresponding redox forms of the clostridial ferredoxins. Characteristics of the contact-shifted resonances observed in partially reducedB. polymyxa ferredoxin I are compatible with a “slow” rate of electron exchange between redox forms, which suggests that the “fast” electron exchange earlier observed in the eight-iron clostridial ferredoxins may derive from an intramolecular component.