Transient binding of photodissociated CO to Cu sub B sup + of eukaryotic cytochrome oxidase at ambient temperature. Direct evidence from time-resolved infrared spectroscopy

Journal Article · Wed Sep 13 00:00:00 EDT 1989 · Journal of the American Chemical Society; (USA)

DOI:https://doi.org/10.1021/ja00201a080· OSTI ID:6717377

Dyer, R B; Einarsdottir, O; Killough, P M; Lopez-Garriga, J J; Woodruff, W H ^[1]

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1. Los Alamos National Lab., NM (USA)

The reactions of CO with the metal centers of cytochrome oxidase exemplify the mechanisms open to O{sub 2} and other small-molecule ligands. In particular, the fast reactions following photodissociation of CO from cytochrome a{sub 3} yield important information about the pathways available to ligands to and from the active site. FTIR studies have demonstrated that, below 180 K, photodissociated CO binds to Cu{sub B}{sup +} both in mitochondrial preparations and in the detergent-solubilized enzyme. We have also observed Cu{sub B}{sup +}-CO in the room temperature FTIR spectrum of cytochrome ba{sub 3} from Thermus thermophilus. In this report we present the first direct, ambient temperature evidence that CO does indeed bind to Cu{sub B}{sup +}. This conclusion is based upon the observation of the transient infrared absorbance due to the C-O stretching vibration of Cu{sub B}{sup +}-CO, following photodissociation of CO from heme a{sub 3}. We observe that the transient Cu{sub B}{sup +}-CO complex equilibrates with its surroundings on a short time scale, losing CO into solution with a half-life of 1.5 {mu}s.

• OSTI ID: 6717377
• Journal Information: Journal of the American Chemical Society; (USA), Vol. 111:19; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
59 BASIC BIOLOGICAL SCIENCES
CARBON MONOXIDE
CYTOCHROME OXIDASE
INFRARED SPECTRA
CALCULATION METHODS
COPPER
DATA ANALYSIS
EXPERIMENTAL DATA
LIGANDS
MEASURING INSTRUMENTS
MEASURING METHODS
PHOTOCHEMICAL REACTIONS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
DATA
ELEMENTS
ENZYMES
HAEM DEHYDROGENASES
INFORMATION
METALS
NUMERICAL DATA
OXIDES
OXIDOREDUCTASES
OXYGEN COMPOUNDS
SPECTRA
TRANSITION ELEMENTS
400200* - Inorganic
Organic
& Physical Chemistry
550200 - Biochemistry