Reaction of cytochrome bo3, with oxygen: Extra redox center(s) are present in the protein

Jianling Wang, Jon Rumbley, Yuan Chin Ching, Satoshi Takahashi, Robert B. Gennis, Denis L. Rousseau

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

The reaction of oxygen with cytochrome bo3, a quinol oxidase from Escherichia coli, has been studied by resonance Raman scattering after initiation of the reaction by CO photolysis in a continuous flow apparatus and by directly mixing the enzyme with oxygen. The high-frequency region of the spectrum was monitored to determine the time evolution of the spin, oxidation, and coordination states of heme O and the oxidation state of heme B by using newly established marker lines for each heme. Three phases of the reaction were detected. In phase I, complete in 75 μs, O2 reacted with heme O and formed a low-spin ferric or ferryl adduct without significant oxidation of heme B. In phase II, between 75 and 120 μs, a small fraction of heme B was oxidized. In phase III, at ∼1 s, the majority of heme B was oxidized and heme O reverted to a high-spin ferric state. The high rate of oxygen reduction at heme O to the three- or four-electron reduced level, despite a very low rate of heme B oxidation, indicates that there are electron donors active in the enzyme other than the metal centers. Assays of our enzyme preparations rule out a quinol in the tight binding (QH) site as a possible donor but instead suggest electron donation from the protein matrix, such as from tryptophans or tyrosines. Three Tryptophans (W280, W282, and W331) and one tyrosine (Y288) are postulated as candidates for such a role, and their location near the binuclear center suggests that the donor electrons follow a pathway directly to the heme O-CUB binuclear center without passing through heme B. The donors that participate in the catalytic mechanism in vitro may also play a functional role under physiological conditions.

Original languageEnglish (US)
Pages (from-to)15504-15511
Number of pages8
JournalBiochemistry
Volume34
Issue number47
StatePublished - 1995
Externally publishedYes

Fingerprint

Cytochromes
Heme
Oxidation-Reduction
Oxygen
Electrons
Proteins
Oxidation
Tryptophan
Tyrosine
Enzymes
Hydroquinones
Raman Spectrum Analysis
Photolysis
Enzyme Assays
Binding sites
Carbon Monoxide
Escherichia coli
Raman scattering
Assays
Metals

ASJC Scopus subject areas

  • Biochemistry

Cite this

Wang, J., Rumbley, J., Ching, Y. C., Takahashi, S., Gennis, R. B., & Rousseau, D. L. (1995). Reaction of cytochrome bo3, with oxygen: Extra redox center(s) are present in the protein. Biochemistry, 34(47), 15504-15511.

Reaction of cytochrome bo3, with oxygen : Extra redox center(s) are present in the protein. / Wang, Jianling; Rumbley, Jon; Ching, Yuan Chin; Takahashi, Satoshi; Gennis, Robert B.; Rousseau, Denis L.

In: Biochemistry, Vol. 34, No. 47, 1995, p. 15504-15511.

Research output: Contribution to journalArticle

Wang, J, Rumbley, J, Ching, YC, Takahashi, S, Gennis, RB & Rousseau, DL 1995, 'Reaction of cytochrome bo3, with oxygen: Extra redox center(s) are present in the protein', Biochemistry, vol. 34, no. 47, pp. 15504-15511.
Wang J, Rumbley J, Ching YC, Takahashi S, Gennis RB, Rousseau DL. Reaction of cytochrome bo3, with oxygen: Extra redox center(s) are present in the protein. Biochemistry. 1995;34(47):15504-15511.
Wang, Jianling ; Rumbley, Jon ; Ching, Yuan Chin ; Takahashi, Satoshi ; Gennis, Robert B. ; Rousseau, Denis L. / Reaction of cytochrome bo3, with oxygen : Extra redox center(s) are present in the protein. In: Biochemistry. 1995 ; Vol. 34, No. 47. pp. 15504-15511.
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