2GRF image
Entry Detail
PDB ID:
2GRF
Title:
Crystal structure of Scapharca inaequivalvis HBI, M37V mutant in the absence of ligand
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2006-04-24
Release Date:
2006-05-09
Method Details:
Experimental Method:
Resolution:
2.10 Å
R-Value Free:
0.22
R-Value Work:
0.18
R-Value Observed:
0.18
Space Group:
C 2 2 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Globin-1
Mutations:M37V
Chain IDs:A, B
Chain Length:146
Number of Molecules:2
Biological Source:Scapharca inaequivalvis
Ligand Molecules
Primary Citation
Allosteric action in real time: Time-resolved crystallographic studies of a cooperative dimeric hemoglobin.
Proc.Natl.Acad.Sci.Usa 103 7649 7654 (2006)
PMID: 16684887 DOI: 10.1073/pnas.0509411103

Abstact

Protein allostery provides mechanisms for regulation of biological function at the molecular level. We present here an investigation of global, ligand-induced allosteric transition in a protein by time-resolved x-ray diffraction. The study provides a view of structural changes in single crystals of Scapharca dimeric hemoglobin as they proceed in real time, from 5 ns to 80 micros after ligand photodissociation. A tertiary intermediate structure forms rapidly (<5 ns) as the protein responds to the presence of an unliganded heme within each R-state protein subunit, with key structural changes observed in the heme groups, neighboring residues, and interface water molecules. This intermediate lays a foundation for the concerted tertiary and quaternary structural changes that occur on a microsecond time scale and are associated with the transition to a low-affinity T-state structure. Reversal of these changes shows a considerable lag as a T-like structure persists well after ligand rebinding, suggesting a slow T-to-R transition.

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Primary Citation of related structures