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MetaCyc Compound Class: an electron-transfer quinone

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

Summary:
This class holds quinones that are involved in electron transfer within membranes.

Quinones are organic compounds derived from aromatic compound, with two carbonyl groups incorporated into the ring structure with rearrangement of the double bonds where necessary. A classic example of a quinone is 1,4-benzoquinone. Quinones are commonly named with a prefix that indicates the parent aromatic hydrocarbon (for example, "benzo-" for benzene, "naphtho-" for naphthalene, and "anthra-" for anthracene) with a "-quinone" suffix.

Several types of quinones serve as electron acceptors in electron transport chains. Quinones can carry two electrons, and when fully reduced they are referred to as quinols. The addition of a single H atom to a quinone results in formation of a free radical called a semiquinone.

Many quinone derivatives often have other biological activities, such as vitamin K.

an electron-transfer quinone compound structure

Child Classes: a demethylmenaquinone (8) , a menaquinone (17) , a plastoquinone (1) , a rhodoquinone (2) , an anthraquinone (2) , an ubiquinone (9)

Instances:
caldariellaquinone ,
phylloquinone

SMILES: C1([R1])(=C([R4])C(=O)C([R3])=C([R2])C(=O)1)

Reactions known to consume the compound:

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

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

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

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

TCA cycle I (prokaryotic) :
(S)-malate[in] + an electron-transfer quinone[membrane] → oxaloacetate[in] + an electron-transfer quinol[membrane]

TCA cycle IV (2-oxoglutarate decarboxylase) , TCA cycle V (2-oxoglutarate:ferredoxin oxidoreductase) :
succinate[in] + an electron-transfer quinone[membrane] → fumarate[in] + an electron-transfer quinol[membrane]

TCA cycle VII (acetate-producers) :
(S)-malate[in] + an electron-transfer quinone[membrane] → oxaloacetate[in] + an electron-transfer quinol[membrane]
succinate[in] + an electron-transfer quinone[membrane] → fumarate[in] + an electron-transfer quinol[membrane]

trans-4-hydroxy-L-proline degradation I :
trans-4-hydroxy-L-proline[in] + an electron-transfer quinone[membrane] → (3R,5S)-1-pyrroline-3-hydroxy-5-carboxylate[in] + an electron-transfer quinol[membrane] + H+[in]

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

UMP biosynthesis :
(S)-dihydroorotate + an electron-transfer quinone[inner membrane] → orotate + an electron-transfer quinol[inner membrane]

Not in pathways:
NADPH[in] + an electron-transfer quinone[membrane] + H+[in] → NADP+[in] + an electron-transfer quinol[membrane]
an electron-transfer quinone[membrane] + NAD(P)H[in] + H+[in] → an electron-transfer quinol[membrane] + NAD(P)+[in]
sn-glycerol 3-phosphate[in] + an electron-transfer quinone[membrane] → glycerone phosphate[in] + an electron-transfer quinol[membrane]
D-glucopyranose[out] + an electron-transfer quinone[membrane] + 2 H+[in] → D-glucono-1,5-lactone[out] + an electron-transfer quinol[membrane] + 2 H+[out]
a D-amino acid[in] + an electron-transfer quinone[membrane] + H2O[in] → a 2-oxo carboxylate[in] + ammonium[in] + an electron-transfer quinol[membrane]

phenylacetate degradation II (anaerobic) :
phenylacetyl-CoA + 2 a quinone + H2O → 2 a quinol + phenylglyoxylyl-CoA

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

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

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

Not in pathways:
a cyclic alcohol + a quinonea cyclic ketone + a quinol

Not in pathways:
a cyclic alcohol + a quinonea cyclic ketone + a quinol

Reactions known to produce the compound:

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

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

Not in pathways:
2 an oxidized c-type cytochrome[out] + an electron-transfer quinol[membrane] → 2 a reduced c-type cytochrome[out] + an electron-transfer quinone[membrane] + 2 H+[in]

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

Not in pathways:
a secondary alcohol + oxygen → a ketone + hydrogen peroxide

Not in pathways:
a nitroalkane + oxygen + H2O → an aldehyde or ketone + nitrite + hydrogen peroxide + H+

Reactions known to both consume and produce the compound:

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

Not in pathways:
2 a quinone + NADPH + H+ ↔ 2 a semiquinone + NADP+

In Reactions of unknown directionality:

Not in pathways:
an oxidized coenzyme F420 + an electron-transfer quinol = a reduced coenzyme F420 + an electron-transfer quinone
an aldehyde + an electron-transfer quinone + H2O = a carboxylate + an electron-transfer quinol + H+
an (R)-2-hydroxyacid + an electron-transfer quinone = a 2-oxo acid + an electron-transfer quinol
NADH + an electron-transfer quinone + H+ = NAD+ + an electron-transfer quinol
formate + an electron-transfer quinone + H+ = CO2 + an electron-transfer quinol
9,9'-di-cis-ζ-carotene + 2 an electron-transfer quinone = prolycopene + 2 an electron-transfer quinol

Not in pathways:
2 a quinone + NADH + H+ = 2 a semiquinone + NAD+
1-(β-D-ribofuranosyl)-1,4-dihydronicotinamide + a quinone + H+ = a quinol + 1-(β-D ribofuranosyl)nicotinamide

Not in pathways:
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 Redox half-reactions:
an electron-transfer quinone[membrane] + 2 H+[in] + 2 e-[membrane] → an electron-transfer quinol[membrane]

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

Credits:
Created 31-Jan-2011 by Caspi R , SRI International


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 19.0 on Sat May 30, 2015, biocyc14.