| Literature DB >> 2994040 |
P J Stephens, T V Morgan, F Devlin, J E Penner-Hahn, K O Hodgson, R A Scott, C D Stout, B K Burgess.
Abstract
Fe(CN)6(-3) oxidation of the aerobically isolated 7Fe Azotobacter vinelandii ferredoxin I, (7Fe)FdI, is a degradative reaction. Destruction of the [4Fe-4S] cluster occurs first, followed by destruction of the [3Fe-3S] cluster. At a Fe(CN)6(-3)/(7Fe)FdI concentration ratio of 20, the product is a mixture of apoprotein and protein containing only a [3Fe-3S] cluster, (3Fe)FdI. This protein mixture, after partial purification, has been characterized by absorption, CD, magnetic CD, and EPR and Fe x-ray absorption spectroscopies. EPR and magnetic CD spectra provide strong evidence that the [3Fe-3S] cluster in (3Fe)FdI is essentially identical in structure to that in (7Fe)FdI. Analysis of the extended x-ray absorption fine structure (EXAFS) of (3Fe)FdI finds Fe scattering at an average Fe...Fe distance of approximately equal to 2.7 A. The structure of the oxidized [3Fe-3S] cluster in solutions of oxidized (3Fe)FdI, and, by extension, of oxidized (7Fe)FdI, is thus different from that obtained by x-ray crystallography on oxidized (7Fe)FdI. Possible interpretations of this result are discussed.Entities:
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Year: 1985 PMID： 2994040 PMCID： PMC390611 DOI： 10.1073/pnas.82.17.5661
Source DB: PubMed Journal: Proc Natl Acad Sci U S A ISSN： 0027-8424 Impact factor: 11.205