1f5p: Difference between revisions

Revision as of 13:35, 21 February 2008

2.9 ANGSTROM CRYSTAL STRUCTURE OF LAMPREY HEMOGLOBIN THAT HAS BEEN EXPOSED TO CARBON MONOXIDE.

OverviewOverview

The hemoglobins of the Sea Lamprey (Petromyzon marinus) exist in an equilibrium between low affinity oligomers, stabilized by proton binding, and higher affinity monomers, stabilized by oxygen binding. Recent crystallographic analysis revealed that dimerization is coupled with key changes at the ligand binding site with the distal histidine sterically restricting ligand binding in the deoxy dimer but with no significant structural rearrangements on the proximal side. These structural insights led to the hypothesis that oxygen affinity of lamprey hemoglobin is distally regulated. Here we present the 2.9-A crystal structure of deoxygenated lamprey hemoglobin in an orthorhombic crystal form along with the structure of these crystals exposed to carbon monoxide. The hexameric assemblage in this crystal form is very similar to those observed in the previous deoxy structure. Whereas the hydrogen bonding network and packing contacts formed in the dimeric interface of lamprey hemoglobin are largely unaffected by ligand binding, the binding of carbon monoxide induces the distal histidine to swing to positions that would preclude the formation of a stabilizing hydrogen bond with the bound ligand. These results suggest a dual role for the distal histidine and strongly support the hypothesis that ligand affinity in lamprey hemoglobin is distally regulated.

About this StructureAbout this Structure

1F5P is a Single protein structure of sequence from Petromyzon marinus with and as ligands. Full crystallographic information is available from OCA.

ReferenceReference

Crystalline ligand transitions in lamprey hemoglobin. Structural evidence for the regulation of oxygen affinity., Heaslet HA, Royer WE Jr, J Biol Chem. 2001 Jul 13;276(28):26230-6. Epub 2001 May 4. PMID:11340069

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 ==Overview==
-The hemoglobins of the Sea Lamprey (Petromyzon marinus) exist in an, equilibrium between low affinity oligomers, stabilized by proton binding, and higher affinity monomers, stabilized by oxygen binding. Recent, crystallographic analysis revealed that dimerization is coupled with key, changes at the ligand binding site with the distal histidine sterically, restricting ligand binding in the deoxy dimer but with no significant, structural rearrangements on the proximal side. These structural insights, led to the hypothesis that oxygen affinity of lamprey hemoglobin is, distally regulated. Here we present the 2.9-A crystal structure of, deoxygenated lamprey hemoglobin in an orthorhombic crystal form along with, the structure of these crystals exposed to carbon monoxide. The hexameric, assemblage in this crystal form is very similar to those observed in the, previous deoxy structure. Whereas the hydrogen bonding network and packing, contacts formed in the dimeric interface of lamprey hemoglobin are largely, unaffected by ligand binding, the binding of carbon monoxide induces the, distal histidine to swing to positions that would preclude the formation, of a stabilizing hydrogen bond with the bound ligand. These results, suggest a dual role for the distal histidine and strongly support the, hypothesis that ligand affinity in lamprey hemoglobin is distally, regulated.
+The hemoglobins of the Sea Lamprey (Petromyzon marinus) exist in an equilibrium between low affinity oligomers, stabilized by proton binding, and higher affinity monomers, stabilized by oxygen binding. Recent crystallographic analysis revealed that dimerization is coupled with key changes at the ligand binding site with the distal histidine sterically restricting ligand binding in the deoxy dimer but with no significant structural rearrangements on the proximal side. These structural insights led to the hypothesis that oxygen affinity of lamprey hemoglobin is distally regulated. Here we present the 2.9-A crystal structure of deoxygenated lamprey hemoglobin in an orthorhombic crystal form along with the structure of these crystals exposed to carbon monoxide. The hexameric assemblage in this crystal form is very similar to those observed in the previous deoxy structure. Whereas the hydrogen bonding network and packing contacts formed in the dimeric interface of lamprey hemoglobin are largely unaffected by ligand binding, the binding of carbon monoxide induces the distal histidine to swing to positions that would preclude the formation of a stabilizing hydrogen bond with the bound ligand. These results suggest a dual role for the distal histidine and strongly support the hypothesis that ligand affinity in lamprey hemoglobin is distally regulated.
 ==About this Structure==
@@ Line 13: / Line 13: @@
 [[Category: Petromyzon marinus]]
 [[Category: Single protein]]
-[[Category: Heaslet, H.A.]]
+[[Category: Heaslet, H A.]]
-[[Category: Jr., W.E.Royer.]]
+[[Category: Jr., W E.Royer.]]
 [[Category: CMO]]
 [[Category: HEM]]
@@ Line 22: / Line 22: @@
 [[Category: lamprey]]
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri Feb 15 15:46:03 2008''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:35:10 2008''