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PDBsum entry 1f03
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Electron transport
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PDB id
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1f03
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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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Solution structure of cytochrome b(5) mutant (e44/48/56a/d60a) and its interaction with cytochrome c.
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Authors
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Y.Wu,
Y.Wang,
C.Qian,
J.Lu,
E.Li,
W.Wang,
J.Lu,
Y.Xie,
J.Wang,
D.Zhu,
Z.Huang,
W.Tang.
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Ref.
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Eur J Biochem, 2001,
268,
1620-1630.
[DOI no: ]
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PubMed id
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Abstract
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Using 1617 meaningful NOEs with 188 pseudocontact shifts, a family of 35
conformers of oxidized bovine microsomal cytochrome b5 mutant (E44/48/56A/D60A)
has been obtained and is characterized by good resolution (rmsd to the mean
structure are 0.047 +/- 0.007 nm and 0.095 +/- 0.008 nm for backbone and heavy
atoms, respectively). The solution structure of the mutant, when compared with
the X-ray structure of wild-type cytochrome b(5), has no significant changes in
the whole folding and secondary structure. The binding between cytochrome b(5)
and cytochrome c shows that the association constant of the mutant-cytochrome c
complex is much lower than the one for wild-type complex (2.2 x 10(4) M(-1) vs.
5.1 x 10(3) M(-1)). The result suggests the four acidic residues have
substantial effects on the formation of the complex between cytochrome b(5) and
cytochrome c, and therefore it is concluded reasonably that the electrostatic
interaction plays an important role in maintaining the stability and specificity
of the complex formed. The competition between the ferricytochrome b(5) mutant
and [Cr(oxalate)(3)](3-) for ferricytochrome c shows that site III of cytochrome
c, which is a strong binding site to wild-type cytochrome b(5), still binds to
the mutant with relatively weaker strength. Our results indicate that certain
bonding geometries do occur in the interaction between the present mutant and
cytochrome c and these geometries, which should be quite different from the ones
of the Salemme and Northrup models.
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Figure 1.
Fig. 1. Schematic representation of the sequential and
medium-range NOE connectivities involving NH, H  , and H  protons for
the oxidized form of cyt b[5] mutant (E44/48/56A/D60A). The
thickness of the bar indicates the intensity of NOEs.
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Figure 4.
Fig. 4. Ribbon diagrams of the average minimized solution
structures of the bovine oxidized cyt b[5] mutant and X-ray
structure of wild-type cyt b[5] (A and B, respectively). A
stereoview of the superimposed structures of cyt b[5] mutant
(black line) and the wild-type (gray line) is shown (C).
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The above figures are
reprinted
by permission from the Federation of European Biochemical Societies:
Eur J Biochem
(2001,
268,
1620-1630)
copyright 2001.
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