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PDBsum entry 1npf
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Oxygen storage/transport
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PDB id
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1npf
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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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Crystal structures of ferrous horse heart myoglobin complexed with nitric oxide and nitrosoethane.
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Authors
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D.M.Copeland,
A.H.West,
G.B.Richter-Addo.
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Ref.
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Proteins, 2003,
53,
182-192.
[DOI no: ]
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PubMed id
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Abstract
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The interactions of nitric oxide (NO) and organic nitroso compounds with heme
proteins are biologically important, and adduct formation between NO-containing
compounds and myoglobin (Mb) have served as prototypical systems for studies of
these interactions. We have prepared crystals of horse heart (hh) MbNO from
nitrosylation of aqua-metMb crystals, and we have determined the crystal
structure of hh MbNO at a resolution of 1.9 A. The Fe-N-O angle of 147 degrees
in hh MbNO is larger than the corresponding 112 degrees angle previously
determined from the crystal structure of sperm whale MbNO (Brucker et al.,
Proteins 1998;30:352-356) but is similar to the 150 degrees angle determined
from a MS XAFS study of a frozen solution of hh MbNO (Rich et al., J Am Chem Soc
1998;120:10827-10836). The Fe-N(O) bond length of 2.0 A (this work) is longer
than the 1.75 A distance determined from the XAFS study and suggests distal
pocket influences on FeNO geometry. The nitrosyl N atom is located 3.0 A from
the imidazole N(epsilon) atom of the distal His64 residue, suggesting
electrostatic stabilization of the FeNO moiety by His64. The crystal structure
of the nitrosoethane adduct of ferrous hh Mb was determined at a resolution of
1.7 A. The nitroso O atom of the EtNO ligand is located 2.7 A from the imidazole
N(epsilon) atom of His64, suggesting a hydrogen bond interaction between these
groups. To the best of our knowledge, the crystal structure of hh Mb(EtNO) is
the first such determination of a nitrosoalkane adduct of a heme protein.
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Figure 1.
Figure 1. a: F[o]-F[c] omit electron density map contoured at 3
 and
final model showing a side view of the heme environment in hh
MbNO. The dashed yellow line represents the 3.0 Å distance
between N^  of
the distal His64 residue and the N atom of the nitrosyl ligand.
Carbon, oxygen, nitrogen, and iron atoms are colored gray, red,
blue, and brown, respectively. b: Top view of the heme in hh
MbNO, with the NO ligand on the side of the porphyrin ring
facing the viewer. The coloring scheme is the same as in (a)
with the exception of the proximal His93 ligand, which is shown
in yellow for clarity.
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Figure 3.
Figure 3. a: F[o]-F[c] omit electron density map contoured at 3
and
final model showing a side view of the heme environment in hh
Mb(EtNO). The dashed yellow line represents a 2.7 Å
distance between the N^ atom
of the distal His64 residue and the O atom of the nitroso group.
b: View of the heme environment showing the off-axis tilt of the
nitrosoethane ligand. The view is along the nitrosoethane CNO
plane. c: Top view of the heme environment in hh Mb(EtNO). The
EtNO ligand is on the side of the porphyrin ring facing the
viewer.
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The above figures are
reprinted
by permission from John Wiley & Sons, Inc.:
Proteins
(2003,
53,
182-192)
copyright 2003.
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