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PDBsum entry 1vng
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Haloperoxidase
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PDB id
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1vng
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References listed in PDB file
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Key reference
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Title
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X-Ray crystal structures of active site mutants of the vanadium-Containing chloroperoxidase from the fungus curvularia inaequalis.
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Authors
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S.Macedo-Ribeiro,
W.Hemrika,
R.Renirie,
R.Wever,
A.Messerschmidt.
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Ref.
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J Biol Inorg Chem, 1999,
4,
209-219.
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PubMed id
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Abstract
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The X-ray structures of the chloroperoxidase from Curvularia inaequalis,
heterologously expressed in Saccharomyces cerevisiae, have been determined both
in its apo and in its holo forms at 1.66 and 2.11 A resolution, respectively.
The crystal structures reveal that the overall structure of this enzyme remains
nearly unaltered, particularly at the metal binding site. At the active site of
the apo-chloroperoxidase structure a clearly defined sulfate ion was found,
partially stabilised through electrostatic interactions and hydrogen bonds with
positively charged residues involved in the interactions with the vanadate in
the native protein. The vanadate binding pocket seems to form a very rigid frame
stabilising oxyanion binding. The rigidity of this active site matrix is the
result of a large number of hydrogen bonding interactions involving side chains
and the main chain of residues lining the active site. The structures of single
site mutants to alanine of the catalytic residue His404 and the vanadium protein
ligand His496 have also been analysed. Additionally we determined the structural
effects of mutations to alanine of residue Arg360, directly involved in the
compensation of the negative charge of the vanadate group, and of residue Asp292
involved in forming a salt bridge with Arg490 which also interacts with the
vanadate. The enzymatic chlorinating activity is drastically reduced to
approximately 1% in mutants D292A, H404A and H496A. The structures of the
mutants confirm the view of the active site of this chloroperoxidase as a rigid
matrix providing an oxyanion binding site. No large changes are observed at the
active site for any of the analysed mutants. The empty space left by replacement
of large side chains by alanines is usually occupied by a new solvent molecule
which partially replaces the hydrogen bonding interactions to the vanadate. The
new solvent molecules additionally replace part of the interactions the mutated
side chains were making to other residues lining the active site frame. When
this is not possible, another side chain in the proximity of the mutated residue
moves in order to satisfy the hydrogen bonding potential of the residues located
at the active site frame.
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Secondary reference #1
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Title
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X-Ray structure of a vanadium-Containing enzyme: chloroperoxidase from the fungus curvularia inaequalis.
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Authors
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A.Messerschmidt,
R.Wever.
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Ref.
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Proc Natl Acad Sci U S A, 1996,
93,
392-396.
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PubMed id
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