Enzymes
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Name help_outline
a menaquinol
Identifier
CHEBI:18151
Charge
0
Formula
C11H10O2(C5H8)n
Search links
Involved in 53 reaction(s)
Find proteins in UniProtKB for this molecule
Form(s) in this reaction:
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Identifier: RHEA-COMP:9539Polymer name: a menaquinolPolymerization index help_outline nFormula C11H10O2(C5H8)nCharge (0)(0)nMol File for the polymer
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- Name help_outline H+ Identifier CHEBI:15378 Charge 1 Formula H InChIKeyhelp_outline GPRLSGONYQIRFK-UHFFFAOYSA-N SMILEShelp_outline [H+] 2D coordinates Mol file for the small molecule Search links Involved in 9,176 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline O2 Identifier CHEBI:15379 (CAS: 7782-44-7) help_outline Charge 0 Formula O2 InChIKeyhelp_outline MYMOFIZGZYHOMD-UHFFFAOYSA-N SMILEShelp_outline O=O 2D coordinates Mol file for the small molecule Search links Involved in 2,648 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
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Name help_outline
a menaquinone
Identifier
CHEBI:16374
(CAS: 11032-49-8)
help_outline
Charge
0
Formula
(C5H8)nC11H8O2
Search links
Involved in 47 reaction(s)
Find proteins in UniProtKB for this molecule
Form(s) in this reaction:
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Identifier: RHEA-COMP:9537Polymer name: a menaquinonePolymerization index help_outline nFormula C11H8O2(C5H8)nCharge (0)(0)nMol File for the polymer
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- Name help_outline H2O Identifier CHEBI:15377 (Beilstein: 3587155; CAS: 7732-18-5) help_outline Charge 0 Formula H2O InChIKeyhelp_outline XLYOFNOQVPJJNP-UHFFFAOYSA-N SMILEShelp_outline [H]O[H] 2D coordinates Mol file for the small molecule Search links Involved in 6,048 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
RHEA:30259 | RHEA:30260 | RHEA:30261 | RHEA:30262 | |
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Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
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More general form(s) of this reaction
Publications
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The terminal quinol oxidases of Bacillus subtilis have different energy conservation properties.
Lauraeus M., Wikstrom M.
We have analyzed the respiratory chains in the log-arithmic and stationary growth phases of Bacillus subtilis cells grown in rich glucose medium. The cytochrome c branch of the respiratory chain was absent from both types of cells, which used a quinol oxidase branch for respiration. Cytochrome aa3 ... >> More
We have analyzed the respiratory chains in the log-arithmic and stationary growth phases of Bacillus subtilis cells grown in rich glucose medium. The cytochrome c branch of the respiratory chain was absent from both types of cells, which used a quinol oxidase branch for respiration. Cytochrome aa3-600 was found to be the major terminal oxidase in log phase cells. This enzyme was shown to translocate protons across the membrane in addition to the charge separation in the oxidation of quinol. Both cytochromes d and aa3-600 were expressed in the stationary phase. After inhibition of the latter by cyanide, cytochrome d was shown to catalyze charge separation during quinol oxidation, but not to pump protons across the membrane. A CO-binding membrane-bound cytochrome of approximately 17 kDa, called cytochrome b558, was presented in log phase cells. This protein did not exhibit oxidase activity and did not have the characteristics of members of the conserved terminal oxidase family. << Less
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Properties of the menaquinol oxidase (Qox) and of qox deletion mutants of Bacillus subtilis.
Lemma E., Simon J., Schagger H., Kroger A.
Menaquinol oxidase isolated from the membrane of Bacillus subtilis W23 was found to consist of four polypeptides (QoxA, B, C, and D) that were predicted by the sequence of the qox operon of B. subtilis 168 (Santana et al. 1992). The preparation contained 7 mol cytochrome aa3 per g protein, which c ... >> More
Menaquinol oxidase isolated from the membrane of Bacillus subtilis W23 was found to consist of four polypeptides (QoxA, B, C, and D) that were predicted by the sequence of the qox operon of B. subtilis 168 (Santana et al. 1992). The preparation contained 7 mol cytochrome aa3 per g protein, which corresponds to 2 mol heme A per mol enzyme of 144 kDa molecular mass. Respiration with dimethylnaphthoquinol catalyzed by the enzyme was ten times faster than that with menadiol. Activities with more electropositive quinols were negligible. The activity of the enzyme was inhibited by equimolar amounts of HQNO, while antimycin, myxothiazol, and stigmatellin were more than tenfold less effective. When cells of both strains of B. subtilis (W23 and 168) were grown with glucose, quinol respiration was an order of magnitude more active than respiration with N,N,N',N'-tetramethyl-1,4-phenylenediamine plus ascorbate. Surprisingly, the same result was obtained with mutant strains lacking qoxB. As cytochromes a and d were virtually absent, a second quinol oxidase, possibly of the cytochrome o-type, was apparently formed by the mutants. << Less
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Characterization of the semiquinone radical stabilized by the cytochrome aa3-600 menaquinol oxidase of Bacillus subtilis.
Yi S.M., Narasimhulu K.V., Samoilova R.I., Gennis R.B., Dikanov S.A.
Cytochrome aa(3)-600 is one of the principle respiratory oxidases from Bacillus subtilis and is a member of the heme-copper superfamily of oxygen reductases. This enzyme catalyzes the two-electron oxidation of menaquinol and the four-electron reduction of O(2) to 2H(2)O. Cytochrome aa(3)-600 is of ... >> More
Cytochrome aa(3)-600 is one of the principle respiratory oxidases from Bacillus subtilis and is a member of the heme-copper superfamily of oxygen reductases. This enzyme catalyzes the two-electron oxidation of menaquinol and the four-electron reduction of O(2) to 2H(2)O. Cytochrome aa(3)-600 is of interest because it is a very close homologue of the cytochrome bo(3) ubiquinol oxidase from Escherichia coli, except that it uses menaquinol instead of ubiquinol as a substrate. One question of interest is how the proteins differ in response to the differences in structure and electrochemical properties between ubiquinol and menaquinol. Cytochrome bo(3) has a high affinity binding site for ubiquinol that stabilizes a ubi-semiquinone. This has permitted the use of pulsed EPR techniques to investigate the protein interaction with the ubiquinone. The current work initiates studies to characterize the equivalent site in cytochrome aa(3)-600. Cytochrome aa(3)-600 has been cloned and expressed in a His-tagged form in B. subtilis. After isolation of the enzyme in dodecylmaltoside, it is shown that the pure enzyme contains 1 eq of menaquinone-7 and that the enzyme stabilizes a mena-semiquinone. Pulsed EPR studies have shown that there are both similarities as well as significant differences in the interactions of the mena-semiquinone with cytochrome aa(3)-600 in comparison with the ubi-semiquinone in cytochrome bo(3). Our data indicate weaker hydrogen bonds of the menaquinone in cytochrome aa(3)-600 in comparison with ubiquinone in cytochrome bo(3). In addition, the electronic structure of the semiquinone cyt aa(3)-600 is more shifted toward the anionic form from the neutral state in cyt bo(3). << Less