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tag00020                    Pathway                                

Citrate cycle (TCA cycle) - Thermosphaera aggregans
The citrate cycle (TCA cycle, Krebs cycle) is an important aerobic pathway for the final steps of the oxidation of carbohydrates and fatty acids. The cycle starts with acetyl-CoA, the activated form of acetate, derived from glycolysis and pyruvate oxidation for carbohydrates and from beta oxidation of fatty acids. The two-carbon acetyl group in acetyl-CoA is transferred to the four-carbon compound of oxaloacetate to form the six-carbon compound of citrate. In a series of reactions two carbons in citrate are oxidized to CO2 and the reaction pathway supplies NADH for use in the oxidative phosphorylation and other metabolic processes. The pathway also supplies important precursor metabolites including 2-oxoglutarate. At the end of the cycle the remaining four-carbon part is transformed back to oxaloacetate. According to the genome sequence data, many organisms seem to lack genes for the full cycle [MD:M00009], but contain genes for specific segments [MD:M00010 M00011].
Metabolism; Carbohydrate metabolism
BRITE hierarchy
Pathway map
tag00020  Citrate cycle (TCA cycle)

Ortholog table
tag_M00003  Gluconeogenesis, oxaloacetate => fructose-6P [PATH:tag00020]
tag_M00307  Pyruvate oxidation, pyruvate => acetyl-CoA [PATH:tag00020]
Other DBs
BSID: 151625
GO: 0006099
Thermosphaera aggregans [GN:tag]
Tagg_0410  dihydrolipoamide dehydrogenase [KO:K00382] [EC:]
Tagg_0391  2-oxoglutarate ferredoxin oxidoreductase, alpha subunit [KO:K00174] [EC:]
Tagg_1264  2-oxoglutarate synthase [KO:K00174] [EC:]
Tagg_0392  2-oxoglutarate ferredoxin oxidoreductase, beta subunit [KO:K00175] [EC:]
Tagg_1265  pyruvate ferredoxin/flavodoxin oxidoreductase, beta subunit [KO:K00175] [EC:]
Tagg_0393  Pyruvate/ketoisovalerate oxidoreductase [KO:K00177] [EC:]
Tagg_0390  2-oxoglutarate ferredoxin oxidoreductase, delta subunit [KO:K00176] [EC:]
Tagg_1019  succinyl-CoA synthetase (ADP-forming) alpha subunit [KO:K01902] [EC:]
Tagg_1018  succinyl-CoA synthetase (ADP-forming) beta subunit [KO:K01903] [EC:]
Tagg_0833  Pyruvate carboxylase [KO:K01960] [EC:]
Tagg_0003  Phosphoenolpyruvate carboxykinase (GTP) [KO:K01596] [EC:]
Tagg_0387  pyruvate ferredoxin oxidoreductase, alpha subunit [KO:K00169] [EC:]
Tagg_0827  pyruvate flavodoxin/ferredoxin oxidoreductase domain protein [KO:K00169] [EC:]
Tagg_0386  thiamine pyrophosphate protein domain protein TPP-binding protein [KO:K00170] [EC:]
Tagg_0826  thiamine pyrophosphate protein domain protein TPP-binding protein [KO:K00170] [EC:]
Tagg_0389  pyruvate/ketoisovalerate oxidoreductase, gamma subunit [KO:K00172] [EC:]
Tagg_0829  pyruvate/ketoisovalerate oxidoreductase, gamma subunit [KO:K00172] [EC:]
Tagg_0388  pyruvate ferredoxin oxidoreductase, delta subunit [KO:K00171] [EC:]
Tagg_0828  pyruvate ferredoxin/flavodoxin oxidoreductase, delta subunit [KO:K00171] [EC:]
C00022  Pyruvate
C00024  Acetyl-CoA
C00026  2-Oxoglutarate
C00036  Oxaloacetate
C00042  Succinate
C00068  Thiamin diphosphate
C00074  Phosphoenolpyruvate
C00091  Succinyl-CoA
C00122  Fumarate
C00149  (S)-Malate
C00158  Citrate
C00311  Isocitrate
C00417  cis-Aconitate
C05125  2-(alpha-Hydroxyethyl)thiamine diphosphate
C05379  Oxalosuccinate
C05381  3-Carboxy-1-hydroxypropyl-ThPP
C15972  Enzyme N6-(lipoyl)lysine
C15973  Enzyme N6-(dihydrolipoyl)lysine
C16254  [Dihydrolipoyllysine-residue succinyltransferase] S-succinyldihydrolipoyllysine
C16255  [Dihydrolipoyllysine-residue acetyltransferase] S-acetyldihydrolipoyllysine
(map 2)
Nishizuka Y (ed).
[Metabolic Maps] (In Japanese)
Tokyo Kagaku Dojin (1980)
(map 3)
Nishizuka Y, Seyama Y, Ikai A, Ishimura Y, Kawaguchi A (eds).
[Cellular Functions and Metabolic Maps] (In Japanese)
Tokyo Kagaku Dojin (1997)
Michal G.
Biochemical Pathways
Wiley (1999)
KO pathway
LinkDB All DBs

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