1j40
From Proteopedia
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| , resolution 1.45Å | |||||||
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| Ligands: | , , , | ||||||
| Related: | 1J3Y, 1J3Z, 1J41
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| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
Direct observation of photolysis-induced tertiary structural changes in human haemoglobin; Crystal structure of alpha(Ni)-beta(Fe-CO) hemoglobin (laser unphotolysed)
Overview
Human Hb, an alpha2beta2 tetrameric oxygen transport protein that switches from a T (tense) to an R (relaxed) quaternary structure during oxygenation, has long served as a model for studying protein allostery in general. Time-resolved spectroscopic measurements after photodissociation of CO-liganded Hb have played a central role in exploring both protein dynamical responses and molecular cooperativity, but the direct visualization and the structural consequences of photodeligation have not yet been reported. Here we present an x-ray study of structural changes induced by photodissociation of half-liganded T-state and fully liganded R-state human Hb at cryogenic temperatures (25-35 K). On photodissociation of CO, structural changes involving the heme and the F-helix are more marked in the alpha subunit than in the beta subunit, and more subtle in the R state than in the T state. Photodeligation causes a significant sliding motion of the T-state beta heme. Our results establish that the structural basis of the low affinity of the T state is radically different between the subunits, because of differences in the packing and chemical tension at the hemes.
About this Structure
1J40 is a Protein complex structure of sequences from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Direct observation of photolysis-induced tertiary structural changes in hemoglobin., Adachi S, Park SY, Tame JR, Shiro Y, Shibayama N, Proc Natl Acad Sci U S A. 2003 Jun 10;100(12):7039-44. Epub 2003 May 28. PMID:12773618
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