ISSN:
1572-8773
Keywords:
Ferredoxin
;
Clostridium pasteurianum
;
Cobalt derivative
;
ERP
;
NMR
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Summary Ferredoxin fromClostridium pasteurianum substituted with two Co atoms did not give any cobalt EPR signal at 8 K as isolated, but upon reduction with sodium dithionite, a broad signal appeared withg values that indicate highspin (S=3/2) Co(II). These signals were distinct from Co(II)-dithiothreitol signals, and disappeared upon reoxidation with air. Under anaerobic incubation of apoferredoxin with Co(II), a green derivative showed a visible spectrum typical of tetrahedral Co(Il)-thiolate coordination, which shifted dramatically upon exposure to air. The1H-NMR spectrum of the aerobically isolated protein is reported at 300 MHz; magnetic susceptibility measurements were indicative of a diamagnetic species. These spectroscopic studies indicate that Co(II)-substituted ferredoxin is oxidized to low-spin Co(III)-ferredoxin in the presence of sulfide and oxygen. The diamagnetic Co(III) state could reversibly be reduced to highspin Co(II) by sodium dithionite.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01142551
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