1COH

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

Summary for 1COH

• Entry DOI: 10.2210/pdb1coh/pdb
• Descriptor: HEMOGLOBIN (FERROUS CARBONMONOXY) (ALPHA CHAIN), HEMOGLOBIN (COBALTOUS DEOXY) (BETA CHAIN), PROTOPORPHYRIN IX CONTAINING FE, ... (6 entities in total)
• Functional Keywords: oxygen transport
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 4
• Total formula weight: 64609.25

Authors

Luisi, B. (deposition date: 1989-01-13, release date: 1990-01-15, Last modification date: 2024-05-22)

Primary citation

Luisi, B.,Shibayama, N.
Structure of haemoglobin in the deoxy quaternary state with ligand bound at the alpha haems.
J.Mol.Biol., 206:723-736, 1989

PubMed Abstract: 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.

PubMed: 2738915
DOI: 10.1016/0022-2836(89)90579-2

Experimental method

X-RAY DIFFRACTION (2.9 Å)