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EC 4.2.1.20 Details
show Brenda entryEC number
4.2.1.20
Accepted name
tryptophan synthase
Reaction
L-serine + 1-C-(indol-3-yl)glycerol 3-phosphate = L-tryptophan + D-glyceraldehyde 3-phosphate + H2O (overall reaction);;(1a) 1-C-(indol-3-yl)glycerol 3-phosphate = indole + D-glyceraldehyde 3-phosphate;;(1b) L-serine + indole = L-tryptophan + H2O
Other name(s)
L-tryptophan synthetase,
indoleglycerol phosphate aldolase,
tryptophan desmolase,
tryptophan synthetase,
L-serine hydro-lyase (adding indoleglycerol-phosphate),
L-serine hydro-lyase [adding 1-C-(indol-3-yl)glycerol 3-phosphate, L-tryptophan and glyceraldehyde-3-phosphate-forming]
Systematic name
L-serine hydro-lyase [adding 1-C-(indol-3-yl)glycerol 3-phosphate, L-tryptophan and D-glyceraldehyde-3-phosphate-forming]
CAS registry number
9014-52-2
Comment
A pyridoxal-phosphate protein. The α-subunit catalyses the conversion of 1-C-(indol-3-yl)glycerol 3-phosphate to indole and D-glyceraldehyde 3-phosphate (this reaction was included formerly under EC 4.1.2.8). 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 2.4.2.18 (anthranilate phosphoribosyltransferase), EC 4.1.1.48 (indole-3-glycerol-phosphate synthase), EC 4.1.3.27 (anthranilate synthase) and EC 5.3.1.24 (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 4.2.1.122). That enzyme cannot combine with the α unit of EC 4.2.1.20 to form a complex.
History
created 1961, modified 1976, modified 2002, modified 2011
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1 Oxidoreductases
4 Lyases
4.2.1.13 created 1961, deleted 2001 4.2.1.14 created 1961, deleted 2001 4.2.1.15 created 1961, deleted 1972 4.2.1.16 created 1961, deleted 2001 4.2.1.21 created 1961, deleted 1964 4.2.1.23 created 1961, deleted 1972 4.2.1.26 created 1965, deleted 2002 4.2.1.29 created 1965, deleted 2004 4.2.1.37 created 1972, deleted 1992 4.2.1.38 created 1972, deleted 2001 4.2.1.63 created 1972, deleted 1978 4.2.1.64 created 1972, deleted 1978 4.2.1.71 created 1978, modified 1989, modified 2000, deleted 2004 4.2.1.72 created 1978, deleted 2000 4.2.1.86 created 1989, deleted 2004 4.2.1.102 created 2001, deleted 2001
