Acta Botanica Sinica Volume 30 Issue 1, Pages .
Studies on the Circular Dichroism (CD) and Electron Paramaguetic Resonance(EPR) Spe-ctroscopy of the Partially Oxidized FeMo Protein from Azotobacter vinelandii Nitrogenase

Huang Ju-fu, M. C. Mckenna and P. J. Stephens

Abstract:
After nitrogenase FeMo protein from A. vinelandii was incubated with a large excess (5ĘC6 equivalents) of indigo carmine for 30ĘC60 min., all of P-clusters in the partially oxidized FeMo protein were oxidized, but all of FeMoCo in the protein were still in the reductive state. The oxidized P-clusters in the protein were able to be completely reduced by Na2S2O4(DT) and the reduction was accelerated by methyl viologen (MV). And all of FeMoCo in the protein were firstly oxidized by some oxidants such as methylene blue. The numbers of the redox equivalent of P-cluster and FeMoCo have been obtained by the CD reductive titration of and EPR/ ABS time course on the oxidation of the partially oxidizeA FeMo protein, respectivelly.

Keywords:
Circular dichroism (CD); Electron paramagnetic resonance (EPR); In- digo carmine (IC); Redox of FeMo protein
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