Similar CO binding sites in bacterial cytochrome bo and mammalian cytochrome c oxidase

Journal Article · Wed Apr 21 00:00:00 EDT 1993 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00061a072· OSTI ID:6282472

Wang, Jianling; Ching, Yuanchin; Rousseau, D L ^[1]; Hill, J J; Rumbley, J; Gennis, R B ^[2]

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1. AT T Bell Labs., Murray Hill, NJ (United States)
2. Univ. of Illinois, Urbana (United States)

Properties of the active site of terminal oxidation may be studied by examining the stable carbyn monoxide-bound adducts. The resonance Raman and the infrared absorption spectra of CO-bound mammalian cytochrome c oxidase have revealed several structural characteristics of the heme pocket. The cytochrome bo complex is a terminal ubiquinol oxidase from aerobically grown Escherichia coli. The complex contains three known redox centers: two heme groups and one copper atom. One of the hemes, termed cytochrome b[sub 563.5], is low spin and is analogous to cytochrome a in mammalian oxidases. The other heme (cytochrome o) and a nearby copper atom form a binuclear binding site for O[sub 2] or CO that is analogous to the cytochrome a[sub 3]-Cu[sub B] binuclear binding site in mammalian oxidases. The frequencies of the CO-sensitive modes which are detected in cytochrome bo are qualitatively similar to the corresponding frequencies found in the CO-bound cytochrome a[sub 3]. Thus, these data confirm the similarity in the properties of the active sites in these two terminal oxidases. The data substantiate the validity of utilizing site-directed mutagenesis experiments in cytochrome bo to draw inferences concerning the properties of cytochrome aa[sub 3]. Furthermore, the frequencies of the modes involving the bound CO underscore the conclusion that if the proximal ligand in the CO adduct is histidine, features of its bonding to the iron atom of the heme are unique among the histidine-coordinated heme proteins that have been studied to date. The relatively high frequencies for both the Fe-CO and the C-O stretching modes indicate an anomalously weak proximal ligand-iron bond. The small frequency differences between the CO-isotope-sensitive modes in cytochrome bo and cytochrome aa[sub 3] do indicate that the binuclear site of the bacterial enzyme, while similar, is not identical to its mammalian counterpart. 15 refs., 1 fig.

• OSTI ID: 6282472
• Journal Information: Journal of the American Chemical Society; (United States), Vol. 115:8; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CYTOCHROME OXIDASE
MOLECULAR STRUCTURE
SPECTROSCOPY
CARBON MONOXIDE
ENZYMES
RAMAN SPECTRA
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
HAEM DEHYDROGENASES
ORGANIC COMPOUNDS
OXIDES
OXIDOREDUCTASES
OXYGEN COMPOUNDS
PROTEINS
SPECTRA
550200* - Biochemistry
400201 - Chemical & Physicochemical Properties