KEGG   PATHWAY: ppd00020Help
ppd00020                    Pathway                                

Citrate cycle (TCA cycle) - Pelobacter propionicus
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
ppd00020  Citrate cycle (TCA cycle)

Ortholog table
ppd_M00003  Gluconeogenesis, oxaloacetate => fructose-6P [PATH:ppd00020]
ppd_M00009  Citrate cycle (TCA cycle, Krebs cycle) [PATH:ppd00020]
ppd_M00010  Citrate cycle, first carbon oxidation, oxaloacetate => 2-oxoglutarate [PATH:ppd00020]
ppd_M00011  Citrate cycle, second carbon oxidation, 2-oxoglutarate => oxaloacetate [PATH:ppd00020]
ppd_M00307  Pyruvate oxidation, pyruvate => acetyl-CoA [PATH:ppd00020]
Other DBs
BSID: 42868
GO: 0006099
Pelobacter propionicus [GN:ppd]
Ppro_1134  citrate synthase [KO:K01647] [EC:]
Ppro_1692  aconitase [KO:K01682] [EC:]
Ppro_0452  isocitrate dehydrogenase (NADP) [KO:K00031] [EC:]
Ppro_1030  dihydrolipoamide dehydrogenase [KO:K00382] [EC:]
Ppro_2325  2-oxoglutarate ferredoxin oxidoreductase, alpha subunit [KO:K00174] [EC:]
Ppro_0549  pyruvate flavodoxin/ferredoxin oxidoreductase domain protein [KO:K00174] [EC:]
Ppro_2324  2-oxoglutarate ferredoxin oxidoreductase, beta subunit [KO:K00175] [EC:]
Ppro_0548  pyruvate ferredoxin/flavodoxin oxidoreductase, beta subunit [KO:K00175] [EC:]
Ppro_2323  2-oxoglutarate ferredoxin oxidoreductase, gamma subunit [KO:K00177] [EC:]
Ppro_2326  4Fe-4S ferredoxin, iron-sulfur binding domain protein [KO:K00176] [EC:]
Ppro_1715  succinyl-CoA synthetase (ADP-forming) alpha subunit [KO:K01902] [EC:]
Ppro_1716  succinyl-CoA synthetase (ADP-forming) beta subunit [KO:K01903] [EC:]
Ppro_2482  succinate dehydrogenase subunit A [KO:K00239] [EC:]
Ppro_2481  succinate dehydrogenase subunit B [KO:K00240] [EC:]
Ppro_2483  succinate dehydrogenase subunit C [KO:K00241]
Ppro_0749  fumarase [KO:K01676] [EC:]
Ppro_2327  malate dehydrogenase (NAD) [KO:K00024] [EC:]
Ppro_1336  pyruvate carboxylase [KO:K01958] [EC:]
Ppro_3603  Phosphoenolpyruvate carboxykinase (ATP) [KO:K01610] [EC:]
Ppro_1027  Pyruvate dehydrogenase (acetyl-transferring) [KO:K00161] [EC:]
Ppro_1026  catalytic domain of components of various dehydrogenase complexes [KO:K00627] [EC:]
Ppro_0324  pyruvate ferredoxin oxidoreductase, alpha subunit [KO:K00169] [EC:]
Ppro_0470  pyruvate flavodoxin/ferredoxin oxidoreductase domain protein [KO:K00169] [EC:]
Ppro_0319  thiamine pyrophosphate enzyme domain protein TPP-binding protein [KO:K00170] [EC:]
Ppro_0325  pyruvate ferredoxin oxidoreductase, beta subunit [KO:K00170] [EC:]
Ppro_0469  thiamine pyrophosphate enzyme domain protein TPP-binding protein [KO:K00170] [EC:]
Ppro_0472  pyruvate ferredoxin oxidoreductase, gamma subunit [KO:K00172] [EC:]
Ppro_0322  pyruvate ferredoxin oxidoreductase, gamma subunit [KO:K00172] [EC:]
Ppro_0323  pyruvate ferredoxin oxidoreductase, delta subunit [KO:K00171] [EC:]
Ppro_0471  pyruvate ferredoxin/flavodoxin oxidoreductase, delta subunit [KO:K00171] [EC:]
Ppro_0298  pyruvate flavodoxin/ferredoxin oxidoreductase domain protein [KO:K03737] [EC:1.2.7.-]
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

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