Information on EC 1.10.3.14 - ubiquinol oxidase (electrogenic, non H+-transporting)

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The enzyme appears in viruses and cellular organisms

EC NUMBER
COMMENTARY hide
1.10.3.14
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RECOMMENDED NAME
GeneOntology No.
ubiquinol oxidase (electrogenic, non H+-transporting)
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
2 ubiquinol + O2 + 4 H+[side 1] = 2 ubiquinone + 2 H2O + 4 H+[side 2]
show the reaction diagram
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PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
NADH to cytochrome bd oxidase electron transfer I
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NADH to cytochrome bd oxidase electron transport II
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pyruvate to cytochrome bd terminal oxidase electron transfer
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succinate to cytochrome bd oxidase electron transfer
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SYSTEMATIC NAME
IUBMB Comments
ubiquinol:O2 oxidoreductase (electrogenic, non H+-transporting)
This terminal oxidase enzyme is unable to pump protons but generates a proton motive force by transmembrane charge separation resulting from utilizing protons and electrons originating from opposite sides of the membrane to generate water. The bioenergetic efficiency (the number of charges driven across the membrane per electron used to reduce oxygen to water) is 1. The bd-I oxidase from the bacterium Escherichia coli is the predominant respiratory oxygen reductase that functions under microaerophilic conditions in that organism. cf. EC 1.10.3.10, ubiquinol oxidase (H+-transporting).
ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
physiological function
Q9L8R6, Q9L8R7 and Q9L8R6
inactivation of cydA or cydB by gene disruption results in loss of d-heme absorbance at 631 nm. Inactivation of cydA has no effect on the ability of Mycobacterium smegmatis to exit from stationary phase at 37 or 42C. No discernible growth defect of the mutant is observed under moderately aerobic conditions, while the mutant displays a significant growth disadvantage when cocultured with the wild type under extreme microaerophilia. The cydA mutant displays a competitive growth disadvantage in the presence of the terminal oxidase inhibitor, cyanide, when cocultured with wild type at 21% air saturation in an oxystat; inactivation of cydA or cydB gene disruption results in loss of d-heme absorbance at 631 nm
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
2 1,4-naphthoquinol + O2 + 4 H+[side 1]
2 1,4-naphthoquinone + 2 H2O + 4 H+[side 2]
show the reaction diagram
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?
2 2,4-dimethoxy-5-methyl-1,4-benzoquinol + O2 + 4 H+[side 1]
2 2,4-dimethoxy-5-methyl-1,4-benzoquinone + 2 H2O + 4 H+[side 2]
show the reaction diagram
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?
2 duroquinol + O2 + 4 H+[side 1]
2 duroquinone + 2 H2O + 4 H+[side 2]
show the reaction diagram
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?
2 menadiol + O2 + 4 H+[side 1]
2 menadione + 2 H2O + 4 H+[side 2]
show the reaction diagram
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?
2 ubiquinol + O2 + 4 H+[side 1]
2 ubiquinone + 2 H2O + 4 H+[side 2]
show the reaction diagram
additional information
?
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NATURAL SUBSTRATES
NATURAL PRODUCTS
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
2 ubiquinol + O2 + 4 H+[side 1]
2 ubiquinone + 2 H2O + 4 H+[side 2]
show the reaction diagram
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respiratory terminal oxidase
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?
COFACTOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
1
substrate 2,4-dimethoxy-5-methyl-1,4-benzoquinol, pH 6.3, 37C
6.2
substrate duroquinol, pH 6.3, 37C
7.7
substrate 1,4-naphtoquinol, pH 6.3, 37C
15.3
substrate menadiol, pH 6.3, 37C
17.1
substrate menadiol, presence of 50 mM NCl, pH 6.3, 37C
17.3
substrate menadiol, presence of 50 mM KCl, pH 6.3, 37C
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY hide
GeneOntology No.
LITERATURE
SOURCE
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the cytochrome bd-I complexis concentrated in mobile patches in the plasma membrane
Manually annotated by BRENDA team
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subnit cydA has nine transmembrane helices with the O2 reactive site near the periplasmic surface. Residue His19, the ligand to the high spin heme b595 component of the oxidase, is located near the periplasmic surface of the protein
Manually annotated by BRENDA team
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
145000
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sedimentation equilibrium study
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
dimer
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1 * 58000, plus 1 * 43000, SDS-PAGE
additional information
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the purified, enzymatically active cytochrome d complex solubilized in Triton X-100 is an alphabeta heterodimer
EXPRESSION
ORGANISM
UNIPROT
LITERATURE
two- to threefold increase in cydAB gene expression upon reduction of the pO2 of the growth medium from 21 to 0.5% air saturation; two- to threefold increase in cydAB gene expression upon reduction of the pO2 of the growth medium from 21 to 0.5% air saturation
Q9L8R6, Q9L8R7 and Q9L8R6
ENGINEERING
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
D239A
mutation in subunit cydA. Mutant is not able to confer the ability to grow aerobically to a strain that has no genomically encoded respiratory oxidases. Heme content similar to wild-type, complete loss of ubiquinol oxidase activity
D239N
mutation in subunit cydA. Mutant is not able to confer the ability to grow aerobically to a strain that has no genomically encoded respiratory oxidases. Heme content similar to wild-type, complete loss of ubiquinol oxidase activity
D29E
mutation in subunit cydB. Mutant is totally inactive, and hemes d and b595 are not present in the isolated enzyme
E107D
mutation in subunit cydA. About 15% of the heme contant of wild-type, complete loss of ubiquinol oxidase activity
E107Q
mutation in transmembrane helix III of subunit cydA. Mutant is totally inactive, but retains its hemes. Residue E107 is protonated at pH 7.6 and is perturbed by the reduction of the heme d/heme b595 binuclear center at the active site
E257A
mutation of an acidic residue of subunit cydA at or near the quinol-binding site, mutation inactivates the enzyme but has no substantial influence on the Fourier transform infrared redox difference spectrum
E99A
mutation in subunit cydA. Mutant is not able to confer the ability to grow aerobically to a strain that has no genomically encoded respiratory oxidases. Complete loss of heme d and heme b595 and of ubiquinol oxidase activity
E99Q
mutation in subunit cydA. Mutant is not able to confer the ability to grow aerobically to a strain that has no genomically encoded respiratory oxidases. Complete loss of heme d and heme b595 and of ubiquinol oxidase activity