PDBsum entry 1ljw

Oxygen storage/transport

PDB id: 1ljw

Contents

Protein chains

141 a.a. *

146 a.a. *

Ligands

CMO-HEM ×2

PO4

Waters ×261

* Residue conservation analysis

PDB id:

1ljw

Name:

Oxygen storage/transport

Title:

Crystal structure of human carbonmonoxy hemoglobin at 2.16 a: a snapshot of the allosteric transition

Structure:

Hemoglobin alpha chain. Chain: a. Hemoglobin beta chain. Chain: b

Source:

Homo sapiens. Human. Organism_taxid: 9606. Tissue: blood. Tissue: blood

Biol. unit:

Tetramer (from PDB file)

Resolution:

2.16Å R-factor: 0.194 R-free: 0.259

Authors:

M.K.Safo,J.C.Burnett,F.N.Musayev,S.Nokuri,D.J.Abraham

Key ref:

M.K.Safo et al. (2002). Structure of human carbonmonoxyhemoglobin at 2.16 A: a snapshot of the allosteric transition. Acta Crystallogr D Biol Crystallogr, 58, 2031-2037. PubMed id: 12454461 DOI: 10.1107/S0907444902015809

Date:

22-Apr-02 Release date: 01-May-02

Protein chain

P69905  (HBA_HUMAN) -  Hemoglobin subunit alpha from Homo sapiens

Seq: 142 a.a.

Struc: 141 a.a.

Protein chain

P68871  (HBB_HUMAN) -  Hemoglobin subunit beta from Homo sapiens

Seq: 147 a.a.

Struc: 146 a.a.

DOI no: 10.1107/S0907444902015809

Acta Crystallogr D Biol Crystallogr 58:2031-2037 (2002)

PubMed id: 12454461

Structure of human carbonmonoxyhemoglobin at 2.16 A: a snapshot of the allosteric transition.

M.K.Safo, J.C.Burnett, F.N.Musayev, S.Nokuri, D.J.Abraham.

ABSTRACT

A 2.16 A resolution structure of high-salt human carbonmonoxyhemoglobin crystallized at pH 6.4 is reported. The quaternary structure is similar to that of 'classic' R-state hemoglobin; however, subtle but significant tertiary structural changes are observed at the alpha(1)beta(2) and symmetrically equivalent alpha(2)beta(1) interfaces--these are the key subunit interfaces that govern the allosteric transition between the R and T states. Specifically, the movement and weakening of two important hydrogen bonds that are diagnostic for R-state structures, beta(2)His97-alpha(1)Thr38 and beta(2)Arg40-alpha(1)Thr41, have been observed. In addition, a phosphate molecule bound between the two beta-subunits (at the entrance to the central water cavity) has been identified and electron density indicates that this molecule occupies two alternate positions that are related by the dyad axis. Both positions superimpose on the 2,3-diphosphoglycerate binding site. One phosphate conformer interacts with beta(2)Asn139, beta(1)His143 and beta(1)His146, while the second interacts with symmetry-related counterparts (beta(1)Asn139, beta(2)His143 and beta(2)His146).

Selected figure(s)

Figure 2.
Figure 2 Stereo figure of the 2F[o] - F[c] electron-density map at the mouth of the -subunit central water cavity showing the crystallographic phosphate and the surrounding residues. The map is contoured at 1.0 .

Figure 4.
Figure 4 Stereo figure of the -subunit water cavity comparing the phosphate binding site of COHbA (cyan) with the 2,3-DPG binding site of [373]1b86 (red) after superposition of the two structures on the dyad axes (as described in the text).

The above figures are reprinted by permission from the IUCr: Acta Crystallogr D Biol Crystallogr (2002, 58, 2031-2037) copyright 2002.

Figures were selected by the author.