KEGG   PATHWAY: pagh00020
pagh00020                   Pathway                                

Citrate cycle (TCA cycle) - Planktothrix agardhii
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
Pathway map
pagh00020  Citrate cycle (TCA cycle)

pagh_M00010  Citrate cycle, first carbon oxidation, oxaloacetate => 2-oxoglutarate [PATH:pagh00020]
pagh_M00307  Pyruvate oxidation, pyruvate => acetyl-CoA [PATH:pagh00020]
Other DBs
GO: 0006099
Planktothrix agardhii [GN:pagh]
NIES204_03590  gltA; citrate synthase [KO:K01647] [EC:]
NIES204_12930  acnB; aconitate hydratase [KO:K01682] [EC:]
NIES204_13050  icd; isocitrate dehydrogenase, Icd [KO:K00031] [EC:]
NIES204_40740  lpdA; dihydrolipoamide dehydrogenase [KO:K00382] [EC:]
NIES204_31560  sucD; succinyl-CoA synthetase alpha chain [KO:K01902] [EC:]
NIES204_31570  sucC; succinyl-CoA synthetase beta chain [KO:K01903] [EC:]
NIES204_06780  putative succinate dehydrogenase flavoprotein [KO:K00239] [EC:]
NIES204_10430  putative succinate dehydrogenase iron-sulfur protein [KO:K00240] [EC:]
NIES204_06120  succinate dehydrogenase subunit C [KO:K00241]
NIES204_08680  fumC; fumarate hydratase [KO:K01679] [EC:]
NIES204_12790  malate dehydrogenase [KO:K00024] [EC:]
NIES204_31380  pyruvate dehydrogenase E1 alpha subunit [KO:K00161] [EC:]
NIES204_22400  pdhB; pyruvate dehydrogenase E1 beta subunit [KO:K00162] [EC:]
NIES204_05520  branched-chain alpha-keto acid dehydrogenase subunit E2 [KO:K00627] [EC:]
NIES204_36810  nifJ; pyruvate flavodoxin oxidoreductase [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)
pagh00010  Glycolysis / Gluconeogenesis
pagh00053  Ascorbate and aldarate metabolism
pagh00061  Fatty acid biosynthesis
pagh00071  Fatty acid degradation
pagh00220  Arginine biosynthesis
pagh00250  Alanine, aspartate and glutamate metabolism
pagh00280  Valine, leucine and isoleucine degradation
pagh00350  Tyrosine metabolism
pagh00471  D-Glutamine and D-glutamate metabolism
pagh00630  Glyoxylate and dicarboxylate metabolism
KO pathway

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