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PDBsum entry 2b2s
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Oxidoreductase
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PDB id
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2b2s
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References listed in PDB file
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Key reference
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Title
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A molecular switch and electronic circuit modulate catalase activity in catalase-Peroxidases.
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Authors
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X.Carpena,
B.Wiseman,
T.Deemagarn,
R.Singh,
J.Switala,
A.Ivancich,
I.Fita,
P.C.Loewen.
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Ref.
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EMBO Rep, 2005,
6,
1156-1162.
[DOI no: ]
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PubMed id
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Abstract
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The catalase reaction of catalase-peroxidases involves catalase-specific
features built into a peroxidase core. An arginine, 20 A from the active-site
heme, acts as a molecular switch moving between two conformations, one that
activates heme oxidation and one that activates oxoferryl heme reduction by
H(2)O(2), facilitating the catalatic pathway in a peroxidase. The influence of
the arginine is imparted to the heme through its association with or
dissociation from a tyrosinate that modulates reactivity through a Met-Tyr-Trp
crosslinked adduct and a pi electron interaction of the heme with the adduct Trp.
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Figure 2.
Figure 2 View of the 2F[o]-F[c] electron density maps in the
vicinity of Arg 426 modelled at  =1.0.
(A) BpKatG at pH 5.6 exhibits conformations R and Y at a ratio
of approximately 70:30. (B) BpKatG soaked with peroxoacetic acid
as in Figure 1 exhibits 100% conformation R. (C) Native BpKatG
at pH 8.0 exhibits 100% conformation Y. Panel (D) shows the
cavity containing Arg 426 including the two conformations of the
Arg 426 side chain.
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Figure 5.
Figure 5 Scheme showing changes in electron flux in the adduct
and heme under the influence of Arg 426 in conformations Y (A)
and R (B). Conformation Y induces electron flux (red arrow) away
from the heme, favouring its reduction, whereas conformation R
induces electron flux towards the heme, favouring its oxidation.
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The above figures are
reprinted
by permission from Macmillan Publishers Ltd:
EMBO Rep
(2005,
6,
1156-1162)
copyright 2005.
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