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PDBsum entry 1ezv
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Oxidoreductase/electron transport
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PDB id
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1ezv
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Contents |
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430 a.a.
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352 a.a.
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385 a.a.
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245 a.a.
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185 a.a.
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74 a.a.
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125 a.a.
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93 a.a.
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55 a.a.
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127 a.a.
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107 a.a.
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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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Structure at 2.3 a resolution of the cytochrome bc(1) complex from the yeast saccharomyces cerevisiae co-Crystallized with an antibody fv fragment.
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Authors
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C.Hunte,
J.Koepke,
C.Lange,
T.Rossmanith,
H.Michel.
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Ref.
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Structure, 2000,
8,
669-684.
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PubMed id
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Abstract
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BACKGROUND: The cytochrome bc(1) complex is part of the energy conversion
machinery of the respiratory and photosynthetic electron transfer chains. This
integral membrane protein complex catalyzes electron transfer from ubiquinol to
cytochrome c. It couples the electron transfer to the electrogenic translocation
of protons across the membrane via a so-called Q cycle mechanism. RESULTS: The
cytochrome bc(1) complex from the yeast Saccharomyces cerevisiae was
crystallized together with a bound antibody Fv fragment. The structure was
determined at 2.3 A resolution using multiple isomorphous replacement, and
refined to a crystallographic R factor of 22.2% (R(free) = 25.4%). The complex
is present as a homodimer. Each 'monomer' of the refined model includes 2178
amino acid residues of subunits COR1, QCR2, COB, CYT1, RIP1, QCR6, QCR7, QCR8
and QCR9 of the cytochrome bc(1) complex and of the polypeptides V(H) and V(L)
of the Fv fragment, the cofactors heme b(H), heme b(L), heme c(1), the [2Fe-2S]
cluster and 346 water molecules. The Fv fragment binds to the extrinsic domain
of the [2Fe-2S] Rieske protein and is essential for formation of the crystal
lattice. CONCLUSIONS: The approach to crystallize membrane proteins as complexes
with specific antibody fragments appears to be of general importance. The
structure of the yeast cytochrome bc(1) complex reveals in detail the binding
sites of the natural substrate coenzyme Q6 and the inhibitor stigmatellin.
Buried water molecules close to the binding sites suggest possible pathways for
proton uptake and release. A comparison with other cytochrome bc(1) complexes
shows features that are specific to yeast.
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