|Superclasses:||Reactions Classified By Conversion Type → Simple Reactions → Chemical Reactions|
|Reactions Classified By Substrate → Small-Molecule Reactions|
EC Number: 220.127.116.11
Enzymes and Genes:
tryptophan synthase, β subunit dimer : trpB ( Escherichia coli K-12 substr. MG1655 )
tryptophan synthase : TSBType2 ( Arabidopsis thaliana col )
tryptophan synthase, beta subunit : TSB1 ( Arabidopsis thaliana col )
tryptophan synthase β subunit dimer : trpB ( Thermococcus kodakarensis )
tryptophan synthase β2 dimer : trpB2 ( Thermotoga maritima )
tryptophan synthase β1 dimer : trpB1 ( Thermotoga maritima )
In Pathway: tryptophan biosynthesis
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.
Mass balance status: Balanced.
Enzyme Commission Primary Name: tryptophan synthase (indole-salvaging)
Enzyme Commission Synonyms: tryptophan synthase β2
Standard Gibbs Free Energy (ΔrG'° in kcal/mol): -15.4869995 [Latendresse13]
Enzyme Commission Summary:
Most mesophilic bacteria have a multimeric tryptophan synthase complex (EC 18.104.22.168) that forms L-tryptophan from L-serine and 1-C-(indol-3-yl)glycerol 3-phosphate via an indole intermediate. This intermediate, which is formed by the α subunits, is transferred in an internal tunnel to the β units, which convert it to tryptophan. In thermophilic organisms the high temperature enhances diffusion and causes the loss of indole. This enzyme, which does not combine with the α unit to form a complex, salvages the lost indole back to L-tryptophan. It has a much lower Km for indole than the β subunit of EC 22.214.171.124.
Hettwer02: Hettwer S, Sterner R (2002). "A novel tryptophan synthase beta-subunit from the hyperthermophile Thermotoga maritima. Quaternary structure, steady-state kinetics, and putative physiological role." J Biol Chem 277(10);8194-201. PMID: 11756459
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