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Evidence for N coordination to Fe in the [2Fe‐2S] center in yeast mitochondrial complex III Comparison with similar findings for analogous bacterial [2Fe‐2S] proteins
Author(s) -
Telser Joshua,
Hoffman Brian M.,
LoBrutto Russell,
Ohnishi Tomoko,
Tsai Ah-Lim,
Simpkin David,
Palmer Graham
Publication year - 1987
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(87)80024-8
Subject(s) - electron paramagnetic resonance , iron–sulfur cluster , protein subunit , crystallography , chemistry , cluster (spacecraft) , redox , site directed spin labeling , stereochemistry , nuclear magnetic resonance , biochemistry , inorganic chemistry , enzyme , gene , physics , computer science , programming language
Yeast mitochondrial complex III contains a subunit with a [2Fe‐2S] cluster (the Rieske center) that has unusual physical and chemical properties. For apparently similar centers isolated from bacteria, it has been shown by electron nuclear double resonance (ENDOR) and electron spin echo envelope modulation (ESEEM) measurements that these [2Fe‐2S] centers are coordinated by at least one and probably two nitrogen ligands. This work describes similar ENDOR and ESEEM studies on the intact mitochondrial complex. We find that this [2Fe‐2S] cluster exhibits ESEEM and ENDOR properties that appear to be indistinguishable from those observed with the isolated bacterial systems. Furthermore, changes in EPR lineshape that occur as complex III is progressively reduced are not accompanied by any changes in the nitrogen coupling parameters. This spectroscopic evidence for nitrogen coordination is supported by published sequence data on four Rieske iron‐sulfur subunits. It seems likely that this is a general characteristic of such [2Fe‐2S] redox active centers.