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Iron-sulfur stoichiometry and structure of iron-sulfur clusters in three-iron proteins: evidence for [3Fe-4S] clusters.
Proc Natl Acad Sci U S A. 1983 Jan; 80(2):393-6.PN

Abstract

Beef heart aconitase contains 3Fe clusters in its inactive and 4Fe clusters in its active form. The fully active form can be restored from the inactive one by insertion of Fe(2+), whereas S(2-) is not required. Chemical analyses for iron and labile sulfide yield Fe/S(2-) ratios of 0.66-0.74 for the inactive and 0.90-1.03 for the active form. Sulfane sulfur (S(0)) was not detected. We propose on the basis of these data that the inactive form may arise from the active one by loss of one iron only per cluster with the sulfur remaining as S(2-) in a [3Fe-4S] structure. Measurements by extended x-ray absorption fine structure (EXAFS) spectroscopy on the 3Fe form of aconitase yield a Fe..S distance of 2.24 A and a Fe..Fe distance of 2.71 A. This Fe..Fe distance is in agreement with that obtained by EXAFS on ferredoxin II of Desulfovibrio gigas, another 3Fe protein, but disagrees with Fe..Fe distances observed for the 3Fe cluster of Azotobacter vinelandii ferredoxin I by x-ray diffraction-namely, 4.1 A. We suggest that this difference may be due to the presence of a [3Fe-3S] structure in the Azotobacter ferredoxin I crystals vs. a [3Fe-4S] structure in liquid or frozen solutions of aconitase. The [3Fe-3S] cluster has been shown to have a relatively flat twist-boat structure, whereas a [3Fe-4S] cluster could be expected to essentially maintain the compact structure of the [4Fe-4S] cluster. This would explain the differences in Fe..Fe distances. Two possible structural models for a [3Fe-4S] cluster are discussed.

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Authors

Beinert H
No affiliation info available
Emptage MH
No affiliation info available
Dreyer JL
No affiliation info available
Scott RA
No affiliation info available
Hahn JE
No affiliation info available
Hodgson KO
No affiliation info available
Thomson AJ
No affiliation info available

MeSH

Aconitate HydrataseAnimalsAzotobacterCattleDesulfovibrioElectron Spin Resonance SpectroscopyFerredoxinsFourier AnalysisIron-Sulfur ProteinsMetalloproteinsMitochondria, HeartSpectrum Analysis

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

6300839

Citation

Beinert, H, et al. "Iron-sulfur Stoichiometry and Structure of Iron-sulfur Clusters in Three-iron Proteins: Evidence for [3Fe-4S] Clusters." Proceedings of the National Academy of Sciences of the United States of America, vol. 80, no. 2, 1983, pp. 393-6.
Beinert H, Emptage MH, Dreyer JL, et al. Iron-sulfur stoichiometry and structure of iron-sulfur clusters in three-iron proteins: evidence for [3Fe-4S] clusters. Proc Natl Acad Sci U S A. 1983;80(2):393-6.
Beinert, H., Emptage, M. H., Dreyer, J. L., Scott, R. A., Hahn, J. E., Hodgson, K. O., & Thomson, A. J. (1983). Iron-sulfur stoichiometry and structure of iron-sulfur clusters in three-iron proteins: evidence for [3Fe-4S] clusters. Proceedings of the National Academy of Sciences of the United States of America, 80(2), 393-6.
Beinert H, et al. Iron-sulfur Stoichiometry and Structure of Iron-sulfur Clusters in Three-iron Proteins: Evidence for [3Fe-4S] Clusters. Proc Natl Acad Sci U S A. 1983;80(2):393-6. PubMed PMID: 6300839.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Iron-sulfur stoichiometry and structure of iron-sulfur clusters in three-iron proteins: evidence for [3Fe-4S] clusters. AU - Beinert,H, AU - Emptage,M H, AU - Dreyer,J L, AU - Scott,R A, AU - Hahn,J E, AU - Hodgson,K O, AU - Thomson,A J, PY - 1983/1/1/pubmed PY - 1983/1/1/medline PY - 1983/1/1/entrez SP - 393 EP - 6 JF - Proceedings of the National Academy of Sciences of the United States of America JO - Proc Natl Acad Sci U S A VL - 80 IS - 2 N2 - Beef heart aconitase contains 3Fe clusters in its inactive and 4Fe clusters in its active form. The fully active form can be restored from the inactive one by insertion of Fe(2+), whereas S(2-) is not required. Chemical analyses for iron and labile sulfide yield Fe/S(2-) ratios of 0.66-0.74 for the inactive and 0.90-1.03 for the active form. Sulfane sulfur (S(0)) was not detected. We propose on the basis of these data that the inactive form may arise from the active one by loss of one iron only per cluster with the sulfur remaining as S(2-) in a [3Fe-4S] structure. Measurements by extended x-ray absorption fine structure (EXAFS) spectroscopy on the 3Fe form of aconitase yield a Fe..S distance of 2.24 A and a Fe..Fe distance of 2.71 A. This Fe..Fe distance is in agreement with that obtained by EXAFS on ferredoxin II of Desulfovibrio gigas, another 3Fe protein, but disagrees with Fe..Fe distances observed for the 3Fe cluster of Azotobacter vinelandii ferredoxin I by x-ray diffraction-namely, 4.1 A. We suggest that this difference may be due to the presence of a [3Fe-3S] structure in the Azotobacter ferredoxin I crystals vs. a [3Fe-4S] structure in liquid or frozen solutions of aconitase. The [3Fe-3S] cluster has been shown to have a relatively flat twist-boat structure, whereas a [3Fe-4S] cluster could be expected to essentially maintain the compact structure of the [4Fe-4S] cluster. This would explain the differences in Fe..Fe distances. Two possible structural models for a [3Fe-4S] cluster are discussed. SN - 0027-8424 UR - https://www.unboundmedicine.com/medline/citation/6300839/Iron_sulfur_stoichiometry_and_structure_of_iron_sulfur_clusters_in_three_iron_proteins:_evidence_for_[3Fe_4S]_clusters_ L2 - http://www.pnas.org/cgi/pmidlookup?view=long&pmid=6300839 DB - PRIME DP - Unbound Medicine ER -