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Cytochrome d axial ligand of the bd ‐type terminal quinol oxidase from Escherichia coli
Author(s) -
Tsubaki Motonari,
Uno Tadayuki,
Hori Hiroshi,
Mogi Tatsushi,
Nishimura Yoshifumi,
Anraku Yasuhiro
Publication year - 1993
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(93)80430-3
Subject(s) - chemistry , cytochrome , heme , cytochrome c oxidase , electron paramagnetic resonance , histidine , stereochemistry , cytochrome c , resonance raman spectroscopy , cytochrome c1 , ligand (biochemistry) , photochemistry , coenzyme q – cytochrome c reductase , biochemistry , nuclear magnetic resonance , enzyme , raman spectroscopy , physics , receptor , optics , mitochondrion
Using various spectroscopic techniques, we studied the structure of the dioxygen reduction site of the bd ‐type terminal quinol oxidase in the aerobic respiratory chain of Escherichia coli . Resonance Raman and FT‐IR spectroscopies identified the v (Fe 2+ ‐CO) and v (C‐O) stretching frequencies at 471 and 1980.7 cm −1 , respectively, at the cytochrome d center of the dithionite‐reduced CO‐bound enzyme. The CO ligation in the cytochrome bd complex is considerably different from those of the heme‐copper terminal oxidases. Anaerobic addition of NO to the air‐oxidized enzyme caused an exchange of cytochrome d ‐bound dioxygen with NO leading to an appearance of cytochrome d ‐NO EPR signal. But there is no superhyperfine structure originating from the cytochrome d proximal 14 N ligand in the central resonance of the NO EPR signal. These results suggest that cytochrome d axial ligand of the cytochrome bd complex is likely a histidine residue in an anomalous condition or other than a histidine residue and, therefore, the molecular structure around the dioxygen‐binding site is different from that of the heme‐copper terminal oxidases.