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PDBsum entry 2nox
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Oxidoreductase
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PDB id
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2nox
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References listed in PDB file
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Key reference
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Title
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Crystal structure and mechanism of tryptophan 2,3-Dioxygenase, A heme enzyme involved in tryptophan catabolism and in quinolinate biosynthesis.
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Authors
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Y.Zhang,
S.A.Kang,
T.Mukherjee,
S.Bale,
B.R.Crane,
T.P.Begley,
S.E.Ealick.
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Ref.
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Biochemistry, 2007,
46,
145-155.
[DOI no: ]
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PubMed id
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Abstract
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The structure of tryptophan 2,3-dioxygenase (TDO) from Ralstonia metallidurans
was determined at 2.4 A. TDO catalyzes the irreversible oxidation of
l-tryptophan to N-formyl kynurenine, which is the initial step in tryptophan
catabolism. TDO is a heme-containing enzyme and is highly specific for its
substrate l-tryptophan. The structure is a tetramer with a heme cofactor bound
at each active site. The monomeric fold, as well as the heme binding site, is
similar to that of the large domain of indoleamine 2,3-dioxygenase, an enzyme
that catalyzes the same reaction except with a broader substrate tolerance.
Modeling of the putative (S)-tryptophan hydroperoxide intermediate into the
active site, as well as substrate analogue and mutagenesis studies, are
consistent with a Criegee mechanism for the reaction.
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