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PDBsum entry 2edc
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References listed in PDB file
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Key reference
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Title
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Crystallographic and fluorescence studies of the interaction of haloalkane dehalogenase with halide ions. Studies with halide compounds reveal a halide binding site in the active site.
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Authors
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K.H.Verschueren,
J.Kingma,
H.J.Rozeboom,
K.H.Kalk,
D.B.Janssen,
B.W.Dijkstra.
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Ref.
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Biochemistry, 1993,
32,
9031-9037.
[DOI no: ]
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PubMed id
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Abstract
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Haloalkane dehalogenase from Xanthobacter autotrophicus GJ10 catalyzes the
conversion of 1,2-dichloroethane to 2-chloroethanol and chloride without use of
oxygen or cofactors. The active site is situated in an internal cavity, which is
accessible from the solvent, even in the crystal. Crystal structures of the
dehalogenase enzyme complexed with iodoacetamide, chloroacetamide, iodide, and
chloride at pH 6.2 and 8.2 revealed a halide binding site between the ring NH's
of two tryptophan residues, Trp-125 and Trp-175, located in the active site. The
halide ion lies on the intersection of the planes of the rings of the
tryptophans. The binding of iodide and chloride to haloalkane dehalogenase
caused a strong decrease in protein fluorescence. The decrease could be fitted
to a modified form of the Stern-Volmer equation, indicating the presence of
fluorophors of different accessibilities. Halide binding was much stronger at pH
6.0 than at pH 8.2. Assuming ligand binding to Trp-125 and Trp-175 as the sole
cause of fluorescence quenching, dissociation constants at pH 6.0 with chloride
and iodide were calculated to be 0.49 +/- 0.04 and 0.074 +/- 0.007 mM,
respectively. Detailed structural investigation showed that the halide binding
site probably stabilizes the halide product as well as the negatively charged
transition state occurring during the formation of the covalent intermediate.
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Secondary reference #1
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Title
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Crystal structure of haloalkane dehalogenase: an enzyme to detoxify halogenated alkanes.
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Authors
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S.M.Franken,
H.J.Rozeboom,
K.H.Kalk,
B.W.Dijkstra.
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Ref.
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Embo J, 1991,
10,
1297-1302.
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PubMed id
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Secondary reference #2
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Title
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Crystallization of haloalkane dehalogenase from xanthobacter autotrophicus gj10.
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Authors
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H.J.Rozeboom,
J.Kingma,
D.B.Janssen,
B.W.Dijkstra.
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Ref.
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J Mol Biol, 1988,
200,
611-612.
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PubMed id
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