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discounted EARLY registration ends Dec 31, 2014
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discounted EARLY registration ends Dec 31, 2014
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MetaCyc Compound Class: an ubiquinone

Abbrev Name: UQ

Synonyms: coenzyme-Qn, ubiquinone, Q

Superclasses: a redox electron carrier Membrane-Electron-Carriers an electron-transfer-related quinone
an aldehyde or ketone a ketone a cyclic ketone a quinone an electron-transfer-related quinone

Summary:
The ubiquinones are a group of lipid-soluble benzoquinones involved in electron transport. Their structures have a variable length side chain, which consists of one to twelve mono-unsaturated trans-isoprenoids units, with ten units being the most common in animals. Saccharomyces cerevisiae has 6 units, Haemophilus influenzae Rd KW20 has 7, Escherichia coli K-12 has 8, Synechocystis has 9, Homo sapiens has 10, and Micrococcus luteus has an 11 unit form [Kawamukai02].

The terms ubiquinone/ubiquinol refer to the oxidized/reduced forms, and are often used interchangeably. The forms are readily interconvertable.

Ubiquinone is also known as coenzyme Q, or just Q. The names are often followed by the number of the prenoid units in the side chain (e.g. Q-8), or the number of carbons in the chain. For example, the name Q-8 may be substituted with ubiiquinone(40). Since these carbons occur in repeating units of five, these number are multiples of 5.

Instances:
ubiquinone-0 ,
ubiquinone-1 ,
ubiquinone-2 ,
ubiquinone-4 ,
ubiquinone-6 ,
ubiquinone-7 ,
ubiquinone-8 ,
ubiquinone-9 ,
ubiquinone-10

SMILES: C([R])C(C)=CCC1(=C(C)C(=O)C(OC)=C(OC)C(=O)1)

Unification Links: ChEBI:16389 , KEGG:C00399

Reactions known to consume the compound:

2-chloroacrylate degradation I , D-lactate to cytochrome bo oxidase electron transport , methylglyoxal degradation I , methylglyoxal degradation II :
(R)-lactate + an ubiquinone[inner membrane] → pyruvate + an ubiquinol[inner membrane]

aerobic respiration I (cytochrome c) , aerobic respiration III (alternative oxidase pathway) , methylaspartate cycle , succinate to cytochrome bd oxidase electron transfer , succinate to cytochrome bo oxidase electron transfer , superpathway of glyoxylate cycle and fatty acid degradation , TCA cycle I (prokaryotic) , TCA cycle II (plants and fungi) , TCA cycle III (animals) :
succinate[in] + an ubiquinone[CCO-OUT-CCO-IN] → fumarate[in] + an ubiquinol[CCO-OUT-CCO-IN]

aerobic respiration II (cytochrome c) (yeast) :
NADH[in] + an ubiquinone[CCO-OUT-CCO-IN] + H+[in] → NAD+[in] + an ubiquinol[CCO-OUT-CCO-IN]
succinate[in] + an ubiquinone[CCO-OUT-CCO-IN] → fumarate[in] + an ubiquinol[CCO-OUT-CCO-IN]

caffeine degradation V (bacteria, via trimethylurate) :
caffeine + an ubiquinone + H2O → 1,3,7-trimethylurate + an ubiquinol

Fe(II) oxidation :
2 a reduced CycA1 cytochrome[periplasmic space] + an ubiquinone[inner membrane] + 4 H+ → 2 an oxidized CycA1 cytochrome[periplasmic space] + an ubiquinol[inner membrane] + 2 H+[periplasmic space]

glucose and glucose-1-phosphate degradation , glucose degradation (oxidative) , L-ascorbate biosynthesis VI (engineered pathway) :
D-glucopyranose[periplasmic space] + an ubiquinone[inner membrane] → D-glucono-1,5-lactone[periplasmic space] + an ubiquinol[inner membrane]

glycerol degradation I , glycerol-3-phosphate shuttle , glycerol-3-phosphate to cytochrome bo oxidase electron transfer , glycerophosphodiester degradation :
sn-glycerol 3-phosphate[in] + an ubiquinone[CCO-OUT-CCO-IN] → dihydroxyacetone phosphate[in] + an ubiquinol[CCO-OUT-CCO-IN]

NAD/NADP-NADH/NADPH mitochondrial interconversion (yeast) , NADH to cytochrome bd oxidase electron transport II , NADH to cytochrome bo oxidase electron transfer II :
NADH[in] + an ubiquinone[CCO-OUT-CCO-IN] + H+[in] → NAD+[in] + an ubiquinol[CCO-OUT-CCO-IN]

proline to cytochrome bo oxidase electron transfer :
L-proline + an ubiquinone[inner membrane] → (S)-1-pyrroline-5-carboxylate + an ubiquinol[inner membrane] + H+

pyruvate oxidation pathway , pyruvate to cytochrome bd terminal oxidase electron transfer , pyruvate to cytochrome bo oxidase electron transfer :
pyruvate + an ubiquinone[inner membrane] + H2O → CO2 + acetate + an ubiquinol[inner membrane]

UMP biosynthesis :
(S)-dihydroorotate[in] + an ubiquinone[CCO-OUT-CCO-IN] → orotate[in] + an ubiquinol[CCO-OUT-CCO-IN]

(5R)-carbapenem carboxylate biosynthesis , citrulline biosynthesis , L-Nδ-acetylornithine biosynthesis , proline degradation :
L-proline + an electron-transfer-related quinone[inner membrane] → (S)-1-pyrroline-5-carboxylate + an electron-transfer-related quinol[inner membrane] + H+

4-hydroxymandelate degradation :
(S)-4-hydroxymandelate + an electron-transfer-related quinone → 2-(4-hydroxyphenyl)-2-oxoacetate + an electron-transfer-related quinol

alanine degradation I :
D-alanine + an electron-transfer-related quinone[inner membrane] + H2O → ammonium + pyruvate + an electron-transfer-related quinol[inner membrane]

sulfide oxidation I (sulfide-quinone reductase) :
hydrogen sulfide + an electron-transfer-related quinone → intracellular S0 + an electron-transfer-related quinol

TCA cycle IV (2-oxoglutarate decarboxylase) , TCA cycle V (2-oxoglutarate:ferredoxin oxidoreductase) , TCA cycle VII (acetate-producers) :
succinate[in] + an electron-transfer-related quinone[CCO-OUT-CCO-IN] → fumarate[in] + an electron-transfer-related quinol[CCO-OUT-CCO-IN]

trans-4-hydroxy-L-proline degradation I :
trans-4-hydroxy-L-proline[in] + an electron-transfer-related quinone → pyrroline-hydroxy-carboxylate[in] + an electron-transfer-related quinol + H+[in]

trans-lycopene biosynthesis II (plants) :
7,9,9'-cis-neurosporene + an electron-transfer-related quinone → prolycopene + an electron-transfer-related quinol
9,9'-di-cis-ζ-carotene + an electron-transfer-related quinone → 7,9,9'-cis-neurosporene + an electron-transfer-related quinol

Not in pathways:
(S)-dihydroorotate + an electron-transfer-related quinone[inner membrane] → orotate + an electron-transfer-related quinol[inner membrane]
NADPH + an electron-transfer-related quinone + H+ → NADP+ + an electron-transfer-related quinol
a D-amino acid[in] + an electron-transfer-related quinone[CCO-OUT-CCO-IN] + H2O[in] → a 2-oxo carboxylate[in] + ammonium[in] + an electron-transfer-related quinol[CCO-OUT-CCO-IN]
D-glucopyranose[out] + an electron-transfer-related quinone + 2 H+[in] → D-glucono-1,5-lactone[out] + an electron-transfer-related quinol + 2 H+[out]
sn-glycerol 3-phosphate[in] + an electron-transfer-related quinone[CCO-OUT-CCO-IN] → dihydroxyacetone phosphate[in] + an electron-transfer-related quinol[CCO-OUT-CCO-IN]

quinate degradation I :
L-quinate + a quinone → 3-dehydroquinate + a quinol

shikimate degradation I :
shikimate + a quinone → 3-dehydroshikimate + a quinol

TCA cycle I (prokaryotic) , TCA cycle VII (acetate-producers) :
(S)-malate + a quinone → oxaloacetate + a quinol

thiosulfate oxidation II (to tetrathionate) :
2 thiosulfate + a quinone → tetrathionate + a quinol


a quinone + NAD(P)H + H+ → a quinol + NAD(P)+
a cyclic alcohol + a quinonea cyclic ketone + a quinol


a cyclic alcohol + a quinonea cyclic ketone + a quinol

Reactions known to produce the compound:

aerobic respiration III (alternative oxidase pathway) :
2 an ubiquinol[mitochondrial inner membrane] + oxygen[mitochondrial lumen] → 2 an ubiquinone[mitochondrial inner membrane] + 2 H2O[mitochondrial lumen]

D-lactate to cytochrome bo oxidase electron transport , glycerol-3-phosphate to cytochrome bo oxidase electron transfer , NADH to cytochrome bo oxidase electron transfer I , NADH to cytochrome bo oxidase electron transfer II , proline to cytochrome bo oxidase electron transfer , pyruvate to cytochrome bo oxidase electron transfer , succinate to cytochrome bo oxidase electron transfer :
2 an ubiquinol[inner membrane] + 8 H+ + oxygen → 2 an ubiquinone[inner membrane] + 2 H2O + 8 H+[periplasmic space]

long chain fatty acid ester synthesis for microdiesel production :
ethanol + an ubiquinone ← acetaldehyde + an ubiquinol

NADH to cytochrome bd oxidase electron transfer I , NADH to cytochrome bd oxidase electron transport II , pyruvate to cytochrome bd terminal oxidase electron transfer , succinate to cytochrome bd oxidase electron transfer :
2 an ubiquinol[inner membrane] + 4 H+ + oxygen → 2 an ubiquinone[inner membrane] + 4 H+[periplasmic space] + 2 H2O

Not in pathways:
nitrate[periplasmic space] + an ubiquinol[inner membrane] → nitrite[periplasmic space] + an ubiquinone[inner membrane] + H2O[periplasmic space]

methane oxidation to methanol II :
methane + an electron-transfer-related quinol + oxygen → methanol + an electron-transfer-related quinone + H2O

TCA cycle VI (obligate autotrophs) :
succinate[in] + an electron-transfer-related quinone[CCO-OUT-CCO-IN] ← fumarate[in] + an electron-transfer-related quinol[CCO-OUT-CCO-IN]


2 an oxidized c-type cytochrome[out] + an electron-transfer-related quinol → 2 a reduced c-type cytochrome[out] + an electron-transfer-related quinone + 2 H+[in]

cuticular wax biosynthesis :
a secondary alcohol + an oxidized electron acceptor → a ketone + a reduced electron acceptor


a secondary alcohol + oxygen → a ketone + hydrogen peroxide


a nitroalkane + oxygen + H2O → an aldehyde or ketone + nitrite + hydrogen peroxide + H+

Reactions known to both consume and produce the compound:

aerobic respiration I (cytochrome c) :
2 an oxidized c-type cytochrome[out] + an ubiquinol[CCO-OUT-CCO-IN] + 2 H+[in] ↔ 2 a reduced c-type cytochrome[out] + an ubiquinone[CCO-OUT-CCO-IN] + 4 H+[in]
NADH[in] + an ubiquinone[CCO-OUT-CCO-IN] + 5 H+[in] ↔ NAD+[in] + an ubiquinol[CCO-OUT-CCO-IN] + 4 H+[out]

aerobic respiration II (cytochrome c) (yeast) , ammonia oxidation IV (autotrophic ammonia oxidizers) :
2 an oxidized c-type cytochrome[out] + an ubiquinol[CCO-OUT-CCO-IN] + 2 H+[in] ↔ 2 a reduced c-type cytochrome[out] + an ubiquinone[CCO-OUT-CCO-IN] + 4 H+[in]

aerobic respiration III (alternative oxidase pathway) , Fe(II) oxidation , NAD/NADH phosphorylation and dephosphorylation , NADH to cytochrome bd oxidase electron transfer I , NADH to cytochrome bo oxidase electron transfer I :
NADH[in] + an ubiquinone[CCO-OUT-CCO-IN] + 5 H+[in] ↔ NAD+[in] + an ubiquinol[CCO-OUT-CCO-IN] + 4 H+[out]

nitrate reduction I (denitrification) , nitrate reduction VII (denitrification) :
nitrate[in] + an electron-transfer-related quinol ↔ nitrite[in] + an electron-transfer-related quinone + H2O[in]

Not in pathways:
a quinone + NADPH ↔ a semiquinone + NADP+

In Reactions of unknown directionality:

Not in pathways:
D-proline + an ubiquinone = Δ1-pyrroline-2-carboxylate + an ubiquinol + H+
a reduced electron-transfer flavoprotein + an ubiquinone = an oxidized electron-transfer flavoprotein + an ubiquinol


9,9'-di-cis-ζ-carotene + 2 an electron-transfer-related quinone = prolycopene + 2 an electron-transfer-related quinol
formate + an electron-transfer-related quinone + H+ = CO2 + an electron-transfer-related quinol
NADH + an electron-transfer-related quinone + H+ = NAD+ + an electron-transfer-related quinol
an (R)-2-hydroxyacid + an electron-transfer-related quinone = a 2-oxo acid + an electron-transfer-related quinol
an oxidized coenzyme F420 + an electron-transfer-related quinol = a reduced coenzyme F420 + an electron-transfer-related quinone


phenylacetyl-CoA + 2 a quinone + H2O = 2 a quinol + phenylglyoxylyl-CoA
a quinone + NADH = a semiquinone + NAD+
1-(β-D-ribofuranosyl)-1,4-dihydronicotinamide + a quinone + H+ = a quinol + 1-(β-D ribofuranosyl)nicotinamide


a ketone + NADP+ = an enone + NADPH + H+
a secondary alcohol + an oxidized coenzyme F420 = a ketone + a reduced coenzyme F420
a secondary alcohol + NADP+ = a ketone + NADPH + H+
a secondary alcohol + NAD+ = a ketone + NADH + H+

In Transport reactions:
Na+[in] + NADH + an ubiquinone + H+ → Na+[out] + NAD+ + an ubiquinol

In Redox half-reactions:
an ubiquinone + 2 H+[in] + 2 e- → an ubiquinol ,
an ubiquinone + 2 H+[out] + 2 e- → an ubiquinol ,
an electron-transfer-related quinone + 2 H+[in] + 2 e- → an electron-transfer-related quinol

This compound has been characterized as a cofactor or prosthetic group of the following enzymes: putrescine oxidase

Credits:
Revised 17-Aug-2009 by Caspi R , SRI International


References

Kawamukai02: Kawamukai M (2002). "Biosynthesis, bioproduction and novel roles of ubiquinone." J Biosci Bioeng 94(6);511-7. PMID: 16233343


Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 18.5 on Sun Nov 23, 2014, biocyc14.