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. 1971 Dec;68(12):3015–3020. doi: 10.1073/pnas.68.12.3015

Tetrahedral Iron in the Active Center of Plant Ferredoxins and Beef Adrenodoxin*

William A Eaton †,‡,*,||, Graham Palmer †,‡,*,||, James A Fee †,‡,*,||,§, Tokuji Kimura †,‡,*,||, Walter Lovenberg †,‡,*,||
PMCID: PMC389581  PMID: 4332004

Abstract

The coordination structure of the iron-sulfur complex in spinach ferredoxin and adrenodoxin is investigated by optical spectroscopy. The circular-dichroism and absorption spectra of these two-iron iron-sulfur proteins reveal weak electronic transitions in the near-infrared wavelength range, 0.8-2.5 μm (12,500-4000 cm-1). On the basis of the low absorption intensities and large anisotropy factors, d → d transitions of the iron can be identified in the reduced proteins at about 4000 cm-1 and 6000 cm-1. The low energy of these one-center ligand-field transitions, together with the similarity to the ligand-field spectrum of the one-iron protein rubredoxin, leads to the conclusion that the reduced two-iron iron-sulfur proteins also contain a high-spin ferrous ion in a distorted tetrahedral site.

Keywords: iron-sulfur proteins, rubredoxin, near-infrared circular dichroism, ligand-field spectrum, EPR

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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