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PDBsum entry 1ljw
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Oxygen storage/transport
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PDB id
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1ljw
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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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Structure of human carbonmonoxyhemoglobin at 2.16 a: a snapshot of the allosteric transition.
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Authors
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M.K.Safo,
J.C.Burnett,
F.N.Musayev,
S.Nokuri,
D.J.Abraham.
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Ref.
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Acta Crystallogr D Biol Crystallogr, 2002,
58,
2031-2037.
[DOI no: ]
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PubMed id
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Abstract
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A 2.16 A resolution structure of high-salt human carbonmonoxyhemoglobin
crystallized at pH 6.4 is reported. The quaternary structure is similar to that
of 'classic' R-state hemoglobin; however, subtle but significant tertiary
structural changes are observed at the alpha(1)beta(2) and symmetrically
equivalent alpha(2)beta(1) interfaces--these are the key subunit interfaces that
govern the allosteric transition between the R and T states. Specifically, the
movement and weakening of two important hydrogen bonds that are diagnostic for
R-state structures, beta(2)His97-alpha(1)Thr38 and beta(2)Arg40-alpha(1)Thr41,
have been observed. In addition, a phosphate molecule bound between the two
beta-subunits (at the entrance to the central water cavity) has been identified
and electron density indicates that this molecule occupies two alternate
positions that are related by the dyad axis. Both positions superimpose on the
2,3-diphosphoglycerate binding site. One phosphate conformer interacts with
beta(2)Asn139, beta(1)His143 and beta(1)His146, while the second interacts with
symmetry-related counterparts (beta(1)Asn139, beta(2)His143 and beta(2)His146).
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Figure 2.
Figure 2 Stereo figure of the 2F[o] - F[c] electron-density map
at the mouth of the  -subunit
central water cavity showing the crystallographic phosphate and
the surrounding residues. The map is contoured at 1.0  .
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Figure 4.
Figure 4 Stereo figure of the -subunit
water cavity comparing the phosphate binding site of COHbA
(cyan) with the 2,3-DPG binding site of [373]1b86 (red) after
superposition of the two structures on the dyad axes (as
described in the text).
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The above figures are
reprinted
by permission from the IUCr:
Acta Crystallogr D Biol Crystallogr
(2002,
58,
2031-2037)
copyright 2002.
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