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Low temperature electronic absorption spectra of oxidized and reduced spinach ferredoxins. Evidence for nonequivalent iron(III) sites

Rawlings, Jill and Siiman, Olavi and Gray, Harry B. (1974) Low temperature electronic absorption spectra of oxidized and reduced spinach ferredoxins. Evidence for nonequivalent iron(III) sites. Proceedings of the National Academy of Sciences of the United States of America, 71 (1). pp. 125-127. ISSN 0027-8424. http://resolver.caltech.edu/CaltechAUTHORS:RAWpnas74

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Abstract

The electronic absorption spectra of oxidized and reduced spinach ferredoxins have been measured between 1200 and 600 nm at low temperature in D2O/ethylene glycol glasses. Relatively weak absorption bands are observed at 720, 820, and 920 nm oxidized ferredoxin, and at 652, 820, and 920 nm in reduced ferredoxin. The spectral results show that the two Fe(III) centers in oxidized ferredoxin are not equivalent, and that the 820- and 920-nm bands are associated with the nonreducible site. Assignment of the reducible site as tetrahedral Fe(III) is indicated. The 720-nm (13.9 kcm-1) band in oxidized ferredoxin is attributed to an intensity-enhanced 6A1 → 4T1 d-d transition, whereas the 652-nm (15.3 kcm-1) feature of reduced ferredoxin could be due either to 5E → 3T1 in tetrahedral Fe(II)S4 or an Fe(II) → Fe(III) intervalence excitation.


Item Type:Article
Additional Information:Copyright © 1974 by the National Academy of Sciences. Contributed by Harry B. Gray, October 5, 1973. H.B.G. held a John Simon Guggenheim Fellowship during 1972-1973. Research support was provided by the National Science Foundation. This is contribution no. 4769 from the Arthur Amos Noyes Laboratory.
Subject Keywords:ligand field spectra, iron-sulfur proteins, iron(III) coordination
Record Number:CaltechAUTHORS:RAWpnas74
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:RAWpnas74
Alternative URL:http://www.pnas.org/cgi/content/abstract/71/1/125
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1464
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:21 Jan 2006
Last Modified:26 Dec 2012 08:44

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