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PDBsum entry 1a7u
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Haloperoxidase
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PDB id
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1a7u
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Structural investigation of the cofactor-Free chloroperoxidases.
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Authors
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B.Hofmann,
S.Tölzer,
I.Pelletier,
J.Altenbuchner,
K.H.Van pée,
H.J.Hecht.
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Ref.
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J Mol Biol, 1998,
279,
889-900.
[DOI no: ]
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PubMed id
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Abstract
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The structures of cofactor-free haloperoxidases from Streptomyces aureofaciens,
Streptomyces lividans, and Pseudomonas fluorescens have been determined at
resolutions between 1.9 A and 1.5 A. The structures of two enzymes complexed
with benzoate or propionate identify the binding site for the organic acids
which are required for the haloperoxidase activity. Based on these complexes and
on the structure of an inactive variant, a reaction mechanism is proposed for
the halogenation reaction with peroxoacid and hypohalous acid as reaction
intermediates. Comparison of the structures suggests that a specific halide
binding site is absent in the enzymes but that hydrophobic organic compounds may
fit into the active site pocket for halogenation at preferential sites.
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Figure 3.
Figure 3. Stereo picture of the electron density of the
substrate complexes. The coordinates of the substrate molecules
benzoic acid and propionic acid were left out of the entire
refinement and all map calculations in order to reduce model
bias. The density of the (2F[obs]−F[calc]) map is contoured at
the 1.0 σ level and colored green, the density of the
(F[obs]–F[calc]) difference map is contoured at the 4.0 σ
level and colored blue. (a) Stereo picture of the electron
density for the complex of CPO-T with benzoate. Residual
electron density at Ser98 indicates the alternative, lower
occupancy, side-chain conformation. (b) Stereo picture of the
electron density for the complex of CPO-F with propionate.
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Figure 4.
Figure 4. Stereo picture of the active site of the Met99Thr
variant of CPO-A2. (a) Stereo picture of the electron density
showing the bound chloride ion and the side-chain conformation
of Thr99 in the variant. The density of the (2F[obs]–F[calc])
map is contoured at the 1.0 σ level. (b) Stereo picture of a
superimposition of wild-type CPO-L (C^α trace and carbon atoms
colored dark gray) on the variant (C^α trace colored red and
carbon atoms colored yellow). The chloride ion is colored
magenta. The chloride ion is colored magenta.
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(1998,
279,
889-900)
copyright 1998.
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