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PDBsum entry 2frf
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Oxygen storage/transport
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PDB id
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2frf
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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 the nitrite and nitric oxide complexes of horse heart myoglobin.
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Authors
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D.M.Copeland,
A.S.Soares,
A.H.West,
G.B.Richter-Addo.
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Ref.
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J Inorg Biochem, 2006,
100,
1413-1425.
[DOI no: ]
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PubMed id
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Abstract
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Nitrite is an important species in the global nitrogen cycle, and the nitrite
reductase enzymes convert nitrite to nitric oxide (NO). Recently, it has been
shown that hemoglobin and myoglobin catalyze the reduction of nitrite to NO
under hypoxic conditions. We have determined the 1.20 A resolution crystal
structure of the nitrite adduct of ferric horse heart myoglobin (hh Mb). The
ligand is bound to iron in the nitrito form, and the complex is formulated as
MbIII(ONO-). The Fe-ONO bond length is 1.94 A, and the O-N-O angle is 113
degrees . In addition, the nitrite ligand is stabilized by hydrogen bonding with
the distal His64 residue. We have also determined the 1.30 A resolution crystal
structures of hh MbIINO. When hh MbIINO is prepared from the reaction of
metMbIII with nitrite/dithionite, the FeNO angle is 144 degrees with a Fe-NO
bond length of 1.87 A. However, when prepared from the reaction of NO with
reduced MbII, the FeNO angle is 120 degrees with a Fe-NO bond length of 2.13 A.
This difference in FeNO conformations as a function of preparative method is
reproducible, and suggests a role of the distal pocket in hh MbIINO in
stabilizing local FeNO conformational minima.
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