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PDBsum entry 1ebc
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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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Cyanide binding to lucina pectinata hemoglobin i and to sperm whale myoglobin: an X-Ray crystallographic study.
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Authors
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M.Bolognesi,
C.Rosano,
R.Losso,
A.Borassi,
M.Rizzi,
J.B.Wittenberg,
A.Boffi,
P.Ascenzi.
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Ref.
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Biophys J, 1999,
77,
1093-1099.
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PubMed id
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Abstract
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The x-ray crystal structures of the cyanide derivative of Lucina pectinata
monomeric hemoglobin I (L. pectinata HbI) and sperm whale (Physeter catodon)
myoglobin (Mb), generally taken as reference models for monomeric hemoproteins
carrying hydrogen sulfide and oxygen, respectively, have been determined at 1.9
A (R-factor = 0. 184), and 1.8 A (R-factor = 0.181) resolution, respectively, at
room temperature (lambda = 1.542 A). Moreover, the x-ray crystal structure of
the L. pectinata HbI:cyanide derivative has been studied at 1.4-A resolution
(R-factor = 0.118) and 100 K (on a synchrotron source lambda = 0.998 A). At room
temperature, the cyanide ligand is roughly parallel to the heme plane of L.
pectinata HbI, being located approximately 2.5 A from the iron atom. On the
other hand, the crystal structure of the L. pectinata HbI:cyanide derivative at
100 K shows that the diatomic ligand is coordinated to the iron atom in an
orientation almost perpendicular to the heme (the Fe-C distance being 1.95 A),
adopting a coordination geometry strictly reminescent of that observed in sperm
whale Mb, at room temperature. The unusual cyanide distal site orientation
observed in L. pectinata HbI, at room temperature, may reflect reduction of the
heme Fe(III) atom induced by free radical species during x-ray data collection
using Cu Kalpha radiation.
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