1j41
Direct observation of photolysis-induced tertiary structural changes in human haemoglobin; Crystal structure of alpha(Ni)-beta(Fe) hemoglobin (laser photolysed)
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OverviewOverview
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 StructureAbout this Structure
1J41 is a Protein complex structure of sequences from Homo sapiens with HNI, HEM, CMO and 2FU as ligands. Full crystallographic information is available from OCA.
ReferenceReference
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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