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BIOMD0000000068
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    orgname: EMBL-EBI
  n:
    given: Lukas
    family: Endler
species: metaid_0000017
name: Curien2003_MetThr_synthesis
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species: metaid_0000006
type: SBMLModel
occurs in: http://identifiers.org/taxonomy/3702
units def: metaid_0000013
reaction: metaid_0000010
length unit: length
units def: metaid_0000014
is described by: http://identifiers.org/pubmed/14622248
species: metaid_0000005
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creator:
  ORG:
    orgname: Stellenbosh University
  n:
    given: Jacky L
    family: Snoep
substance units: metaid_0000013
modified:
  W3 CDTF: Wed May 16 11:20:30 BST 2012
volume units: metaid_0000323
area units: area
curated: true
units def: metaid_0000015
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created:
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has part: GO:0009088
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creator:
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    orgname: California Institute of Technology
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notes: This a model from the article: A kinetic model of the branch-point between the methionine and threonine biosynthesis pathways in Arabidopsis thaliana. Curien G, Ravanel S, Dumas R Eur. J. Biochem. 2003 Dec; Volume: 270 (Issue: 23 )]:4615-27 14622248 , Abstract: This work proposes a model of the metabolic branch-point between the methionine and threonine biosynthesis pathways in Arabidopsis thaliana which involves kinetic competition for phosphohomoserine between the allosteric enzyme threonine synthase and the two-substrate enzyme cystathionine gamma-synthase. Threonine synthase is activated by S-adenosylmethionine and inhibited by AMP. Cystathionine gamma-synthase condenses phosphohomoserine to cysteine via a ping-pong mechanism. Reactions are irreversible and inhibited by inorganic phosphate. The modelling procedure included an examination of the kinetic links, the determination of the operating conditions in chloroplasts and the establishment of a computer model using the enzyme rate equations. To test the model, the branch-point was reconstituted with purified enzymes. The computer model showed a partial agreement with the in vitro results. The model was subsequently improved and was then found consistent with flux partition in vitro and in vivo. Under near physiological conditions, S-adenosylmethionine, but not AMP, modulates the partition of a steady-state flux of phosphohomoserine. The computer model indicates a high sensitivity of cystathionine flux to enzyme and S-adenosylmethionine concentrations. Cystathionine flux is sensitive to modulation of threonine flux whereas the reverse is not true. The cystathionine gamma-synthase kinetic mechanism favours a low sensitivity of the fluxes to cysteine. Though sensitivity to inorganic phosphate is low, its concentration conditions the dynamics of the system. Threonine synthase and cystathionine gamma-synthase display similar kinetic efficiencies in the metabolic context considered and are first-order for the phosph…
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name: S-adenosylmethionine
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