1sdl
|
CROSS-LINKED, CARBONMONOXY HEMOGLOBIN A
OverviewOverview
The structural end-points of haemoglobin's transition from its, low-oxygen-affinity (T) to high-oxygen-affinity (R) state, have been well, established by X-ray crystallography, but short-lived intermediates have, proved less amenable to X-ray studies. Here we use chemical crosslinking, to fix these intermediates for structural characterization. We describe, the X-ray structures of three haemoglobins, alpha 2 beta 1S82 beta, alpha, 2 beta 1Tm82 beta and alpha 2 beta 1,82Tm82 beta, which were crosslinked, between the amino groups of residues beta Val1 and beta Lys82 by, 3,3'-stilbenedicarboxylic acid (S) or trimesic acid (Tm) while in the, deoxy state, and saturated with carbon monoxide before crystallization., alpha 2 beta 1S82 beta, which has almost normal oxygen affinity, is, completely in the R-state conformation; however, alpha 2 beta 1Tm82 beta, and alpha 2 beta 1,82Tm82 beta, both of which have low oxygen affinity, have been prevented from completing their transition into the R state and, display many features of a transitional intermediate. These haemoglobins, therefore represent a snapshot of the nascent R state.
About this StructureAbout this Structure
1SDL is a Protein complex structure of sequences from Homo sapiens with HEM, CMO and TMM as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Allosteric transition intermediates modelled by crosslinked haemoglobins., Schumacher MA, Dixon MM, Kluger R, Jones RT, Brennan RG, Nature. 1995 May 4;375(6526):84-7. PMID:7723849
Page seeded by OCA on Thu Nov 8 13:18:06 2007