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PDBsum entry 2bkm
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Oxygen storage
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PDB id
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2bkm
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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 structure and ligand binding properties of the truncated hemoglobin from geobacillus stearothermophilus.
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Authors
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A.Ilari,
P.Kjelgaard,
C.Von wachenfeldt,
B.Catacchio,
E.Chiancone,
A.Boffi.
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Ref.
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Arch Biochem Biophys, 2007,
457,
85-94.
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PubMed id
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Abstract
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A novel truncated hemoglobin has been identified in the thermophilic bacterium
Geobacillus stearothermophilus (Gs-trHb). The protein has been expressed in
Escherichia coli, the 3D crystal structure (at 1.5 Angstroms resolution) and the
ligand binding properties have been determined. The distal heme pocket displays
an array of hydrogen bonding donors to the iron-bound ligands, including Tyr-B10
on one side of the heme pocket and Trp-G8 indole nitrogen on the opposite side.
At variance with the highly similar Bacillus subtilis hemoglobin, Gs-trHb is
dimeric both in the crystal and in solution and displays several unique
structural properties. In the crystal cell, the iron-bound ligand is not
homogeneously distributed within each distal site such that oxygen and an
acetate anion can be resolved with relative occupancies of 50% each.
Accordingly, equilibrium titrations of the oxygenated derivative in solution
with acetate anion yield a partially saturated ferric acetate adduct. Moreover,
the asymmetric unit contains two subunits and sedimentation velocity
ultracentrifugation data confirm that the protein is dimeric.
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