1coh

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spinqualitylabelsall models 1coh, resolution 2.9Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

STRUCTURE OF HAEMOGLOBIN IN THE DEOXY QUATERNARY STATE WITH LIGAND BOUND AT THE ALPHA HAEMS

Overview

We report the X-ray crystal structure of two analogues of human, haemoglobin in the deoxy quaternary (T) state with ligand bound, exclusively at the alpha haems. These models were prepared from symmetric, mixed-metal hybrid haemoglobin molecules. The structures of alpha Fe(II), beta Co(II), its carbonmonoxy derivative alpha Fe(II)CO beta Co(II), and, alpha Fe(II)O2 beta Ni(II) are compared with native deoxy haemoglobin by, difference Fourier syntheses at 2.8, 2.9 and 3.5 A resolution, respectively, and the refined alpha Fe(II)CO beta Co(II) structure is, analysed. In both the native deoxy and liganded T molecules, the mean, plane of the alpha-subunit haem is parallel with the axis of the F helix, but this plane is tilted with respect to the helix axis in the, oxy-quaternary R state. The side-chains of LeuFG3 and ValFG5 sterically, restrict haem tilting in the T state. We propose that strain energy, develops at the contact between the haem and these residues in the, liganded T-state haemoglobin, and that the strain is, in part, responsible, for the low affinity of the T-state alpha haem.

About this Structure

1COH is a Protein complex structure of sequences from Homo sapiens with HEM, CMO and COH as ligands. Full crystallographic information is available from OCA.

Reference

Structure of haemoglobin in the deoxy quaternary state with ligand bound at the alpha haems., Luisi B, Shibayama N, J Mol Biol. 1989 Apr 20;206(4):723-36. PMID:2738915

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