-transparent.png){kind=logo}
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.
H Beinert, and
M H Emptage, and
J L Dreyer, and
R A Scott, and
J E Hahn, and
K O Hodgson, and
A J Thomson
June 2018,
Journal of structural biology,
H Beinert, and
M H Emptage, and
J L Dreyer, and
R A Scott, and
J E Hahn, and
K O Hodgson, and
A J Thomson
June 2018,
Journal of structural biology,
H Beinert, and
M H Emptage, and
J L Dreyer, and
R A Scott, and
J E Hahn, and
K O Hodgson, and
A J Thomson
January 2023,
International journal of molecular sciences,
H Beinert, and
M H Emptage, and
J L Dreyer, and
R A Scott, and
J E Hahn, and
K O Hodgson, and
A J Thomson
April 1983,
Archives of biochemistry and biophysics,
H Beinert, and
M H Emptage, and
J L Dreyer, and
R A Scott, and
J E Hahn, and
K O Hodgson, and
A J Thomson
October 2017,
Journal of structural biology,
H Beinert, and
M H Emptage, and
J L Dreyer, and
R A Scott, and
J E Hahn, and
K O Hodgson, and
A J Thomson
November 1980,
Proceedings of the National Academy of Sciences of the United States of America,
H Beinert, and
M H Emptage, and
J L Dreyer, and
R A Scott, and
J E Hahn, and
K O Hodgson, and
A J Thomson
November 1995,
European journal of biochemistry,
H Beinert, and
M H Emptage, and
J L Dreyer, and
R A Scott, and
J E Hahn, and
K O Hodgson, and
A J Thomson
April 2000,
The Journal of biological chemistry,
H Beinert, and
M H Emptage, and
J L Dreyer, and
R A Scott, and
J E Hahn, and
K O Hodgson, and
A J Thomson
October 1998,
The Biochemical journal,
H Beinert, and
M H Emptage, and
J L Dreyer, and
R A Scott, and
J E Hahn, and
K O Hodgson, and
A J Thomson
September 1985,
Proceedings of the National Academy of Sciences of the United States of America,
