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PDBsum entry 1ibh
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Oxidoreductase
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PDB id
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1ibh
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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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Single mutations at the subunit interface modulate copper reactivity in photobacterium leiognathi cu,Zn superoxide dismutase.
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Authors
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M.E.Stroppolo,
A.Pesce,
M.D'Orazio,
P.O'Neill,
D.Bordo,
C.Rosano,
M.Milani,
A.Battistoni,
M.Bolognesi,
A.Desideri.
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Ref.
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J Mol Biol, 2001,
308,
555-563.
[DOI no: ]
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PubMed id
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Abstract
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The functional properties and X-ray structures of five mutant forms of
Photobacterium leiognathi Cu,Zn superoxide dismutase carrying single mutations
at residues located at the dimer association interface have been investigated.
When compared to the wild-type enzyme, the three-dimensional structures of the
mutants show structural perturbations limited to the proximity of the mutation
sites and substantial identity of active site geometry. Nonetheless, the
catalytic rates of all mutants, measured at neutral pH and low ionic strength by
pulse radiolysis, are higher than that of the wild-type protein. Such enzymatic
activity increase is paralleled by enhanced active site accessibility to
external chelating agents, which, in the mutated enzyme, remove more readily the
active site copper ion. It is concluded that mutations at the prokaryotic Cu,Zn
superoxide dismutase subunit interface can transduce dynamical perturbation to
the active site region, promoting substrate active site accessibility. Such
long-range intramolecular communication effects have not been extensively
described before within the Cu,Zn superoxide dismutase homology family.
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Figure 1.
Figure 1. A schematic view of the PSOD dimer displaying one
enzyme subunit as a van der Waals surface (green), the interface
trapped water molecules (red spheres) and the second subunit
shown as a skeletal C^a trace including the active site Cu,Zn
pair (cyan and purple atoms, respectively). Drawn with Dino.[39]
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Figure 2.
Figure 2. (a) A stereo view of the subunit interface
residues in wild-type PSOD. The blue molecular surface
indicating the enzyme association interface hosts the
side-chains of residues (skeletal side-chains) building up the
subunit contact area. The residues individually mutated in the
present study are drawn in purple and specifically labeled. (b)
The PSOD subunit interface is portrayed as shown in (a),
including five out of the ten interface water molecules (red
spheres) buried once the active dimeric enzyme is assembled
through crystallographic two-fold symmetry. Drawn with Dino.[39]
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2001,
308,
555-563)
copyright 2001.
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