Reaction: L-serine + 1-C-(indol-3-yl)glycerol 3-phosphate = L-tryptophan + glyceraldehyde 3-phosphate + H2O (overall reaction)
(1a) 1-C-(indol-3-yl)glycerol 3-phosphate = indole + glyceraldehyde 3-phosphate
(1b) L-serine + indole = L-tryptophan + H2O
For diagram of reaction click here and mechanism click here
Other name(s): L-tryptophan synthetase; indoleglycerol phosphate aldolase; tryptophan desmolase; tryptophan synthetase; L-serine hydro-lyase (adding indoleglycerol-phosphate)
Systematic name: L-serine hydro-lyase [adding 1-C-(indol-3-yl)glycerol 3-phosphate, L-tryptophan and glyceraldehyde-3-phosphate-forming]
Comments: A pyridoxal-phosphate protein. The α-subunit catalyses the conversion of 1-C-(indol-3-yl)glycerol 3-phosphate to indole and glyceraldehyde 3-phosphate (this reaction was listed formerly as EC 126.96.36.199). The indole migrates to the β-subunit where, in the presence of pyridoxal 5'-phosphate, it is combined with L-serine to form L-tryptophan. In some organisms this enzyme is part of a multifunctional protein that also includes one or more of the enzymes EC 188.8.131.52 (anthranilate phosphoribosyltransferase), EC 184.108.40.206 (indole-3-glycerol-phosphate synthase), EC 220.127.116.11 (anthranilate synthase) and EC 18.104.22.168 (phosphoribosylanthranilate isomerase). In thermophilic organisms, where the high temperature enhances diffusion and causes the loss of indole, a protein similar to the β subunit can be found (EC 22.214.171.124). That enzyme cannot combine with the α unit of EC 126.96.36.199 to form a complex.
Links to other databases: BRENDA, EXPASY, GTD, KEGG, Metacyc, PDB, CAS registry number: 9014-52-2
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