Effects of Decyl-aurachin D and Reversed Electron Transfer in Cytochrome bd
Decyl-aurachin D is a near-stoichiometric inhibitor of cytochrome bd from Azotobacter vinelandii. Interaction of decyl-aurachin D with the oxidase induces a redshift of the α-band and Soret band of a b-type cytochrome, probably b-558, suggesting close proximity of the inhibitor binding site to this...
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Published in | Biochemistry (Easton) Vol. 36; no. 31; pp. 9323 - 9331 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
United States
American Chemical Society
05.08.1997
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Subjects | |
Online Access | Get full text |
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Summary: | Decyl-aurachin D is a near-stoichiometric inhibitor of cytochrome bd from Azotobacter vinelandii. Interaction of decyl-aurachin D with the oxidase induces a redshift of the α-band and Soret band of a b-type cytochrome, probably b-558, suggesting close proximity of the inhibitor binding site to this haem and hence to the proposed quinol binding domain. The compound does not affect the oxygen binding site directly as judged from unchanged CO recombination kinetics to haem d in dithionite-reduced enzyme. Although in the presence of ubiquinol-1 a decyl-aurachin D containing sample generates levels of haem reduction and catalytic intermediates similar to the control, the approach to this steady state is severely inhibited. In addition to the spectral effect on b-558, decyl-aurachin D raises the midpoint potential of haem b-558, but also lowers that of haem b-595. Consistent with the shift in midpoint potentials, electron backflow from haem d to the b-type haems can be observed in decyl-aurachin D inhibited samples following photolysis of the mixed-valence CO-ligated form of the enzyme. The data show that decyl-aurachin D acts on the donor side of haem b-558 without substantially affecting internal electron transfer rates or the oxygen reduction site. |
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Bibliography: | ark:/67375/TPS-805N8S3F-C This work was supported by HFSP (grant ref RG-464/95M). Abstract published in Advance ACS Abstracts, August 1, 1997. istex:3E0E73DB700811C2DC1FA2C57839D7B330A252C2 ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2 |
ISSN: | 0006-2960 1520-4995 |
DOI: | 10.1021/bi970055m |