Properties of two distinct heme centers of cytochrome b561 from bovine chromaffin vesicles studied by EPR, resonance Raman, and ascorbate reduction assay.

Properties of two distinct heme centers of cytochrome b561 from bovine chromaffin vesicles studied by EPR, resonance Raman, and ascorbate reduction assay. Research Abstract Details 

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Properties of two distinct heme centers of cytochrome b561 from bovine chromaffin vesicles studied by EPR, resonance Raman, and ascorbate reduction assay. Abstract Text:

Fusako Takeuchi,Hiroshi Hori,Eiji Obayashi,Yoshitsugu Shiro,Motonari Tsubaki,

Cytochrome b(561) from bovine adrenal chromaffin vesicles contains two hemes b with different midpoint potentials (+150 and +60 mV) and participates in transmembrane electron transport from extravesicular ascorbate to an intravesicular monooxygenase, dopamine beta-hydroxylase. Treatment of oxidized cytochrome b(561) with diethylpyrocarbonate caused a downshift of midpoint potential for the lower component, and this shift was prevented by the presence of ascorbate during the treatment. Present EPR analyses showed that, upon the treatment, the g(z) = 3.69 heme species was converted to a non-ascorbate-reducible form, although its g(z)-value showed no appreciable change. The treatment had no effect on the other heme (the g(z) = 3.13 species). Raman data indicated that the two heme b centers adopt a six-coordinated low-spin state, in both the reduced and oxidized forms. There was no significant effect of diethylpyrocarbonate-treatment on the Raman spectra of either form, but the reducibility by ascorbate differed significantly between the two hemes upon the treatment. The addition of ferrocyanide enhanced both the reduction rate and final reduction level of the diethylpyrocarbonate-treated cytochrome b(561) when ascorbate was used as a reductant. This observation suggests that ferrocyanide scavenges monodehydroascorbate radicals produced by the univalent oxidation of ascorbate and, thereby, increases both the reduction rate and the final reduction level of the heme center on the intravesicular side of the diethylpyrocarbonate-treated cytochrome. These results further clarify the physiological role of this heme center as the electron donor to the monodehydroascorbate radical.

Properties of two distinct heme centers of cytochrome b561 from bovine chromaffin vesicles studied by EPR, resonance Raman, and ascorbate reduction assay. Publishing Authors By Initials

F Takeuchi,H Hori,E Obayashi,Y Shiro,M Tsubaki,

For similar investigative techniques: chemistry, analytical: scattering, radiation: spectrum analysis, raman research abstracts see: investigative techniques: chemistry, analytical: scattering, radiation: spectrum analysis, raman research

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Properties of two distinct heme centers of cytochrome b561 from bovine chromaffin vesicles studied by EPR, resonance Raman, and ascorbate reduction assay. Journal Published:

PUBLICATION TYPE: Research Support, Non-U.S. Gov

Journal: Journal of biochemistry

VOLUME: 135

Page Numbers: 53-64

Journal Abbreviation: J. Biochem.

ISSN: 0021-924X

DAY: 19

MONTH: Jan

YEAR: 2004

Properties of two distinct heme centers of cytochrome b561 from bovine chromaffin vesicles studied by EPR, resonance Raman, and ascorbate reduction assay. Information

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LANGUAGE: eng

NlmUniqueID: 376600

Properties of two distinct heme centers of cytochrome b561 from bovine chromaffin vesicles studied by EPR, resonance Raman, and ascorbate reduction assay. Keywords Mesh Terms:

KEYWORDS: Spectrum Analysis, Raman

MESH TERMS: methods

Chemical & Substance for Abstract: Properties of two distinct heme centers of cytochrome b561 from bovine chromaffin vesicles studied by EPR, resonance Raman, and ascorbate reduction assay. Information

Substance Name: Ascorbic Acid

Registry Number: 50-81-7

Grant and Affiliation Information for Properties of two distinct heme centers of cytochrome b561 from bovine chromaffin vesicles studied by EPR, resonance Raman, and ascorbate reduction assay.

AFFILIATION: Department of Life Science, Graduate School of Science, Himeji Institute of Technology, Kamigoori-cho, Akou-gun, Hyogo 678-1297.

Country: Japan

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MEDLINETA: J Biochem

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