1sdk
From Proteopedia
CROSS-LINKED, CARBONMONOXY HEMOGLOBIN A
Overview
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 Structure
1SDK is a Protein complex structure of sequences from Homo sapiens. Full crystallographic information is available from OCA.
Reference
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 Sat May 3 08:34:42 2008
