1LA6

The crystal structure of Trematomus newnesi hemoglobin in a partial hemichrome state

Summary for 1LA6

• Entry DOI: 10.2210/pdb1la6/pdb
• Related: 1T1N
• Descriptor: Hemoglobin alpha-1 chain, Hemoglobin beta-1/2 chain, PROTOPORPHYRIN IX CONTAINING FE, ... (5 entities in total)
• Functional Keywords: hemichrome, bishistidine complex, oxygen storage-transport complex, oxygen storage/transport
• Biological source: Trematomus newnesi (dusky notothen); More
• Total number of polymer chains: 2
• Total formula weight: 33210.69

Authors

Riccio, A.,Vitagliano, L.,di Prisco, G.,Zagari, A.,Mazzarella, L. (deposition date: 2002-03-28, release date: 2002-07-31, Last modification date: 2023-08-16)

Primary citation

Riccio, A.,Vitagliano, L.,di Prisco, G.,Zagari, A.,Mazzarella, L.
The crystal structure of a tetrameric hemoglobin in a partial hemichrome state
Proc.Natl.Acad.Sci.USA, 99:9801-9806, 2002

PubMed Abstract: Tetrameric hemoglobins are the most widely used systems in studying protein cooperativity. Allosteric effects in hemoglobins arise from the switch between a relaxed (R) state and a tense (T) state occurring upon oxygen release. Here we report the 2.0-A crystal structure of the main hemoglobin component of the Antarctic fish Trematomus newnesi, in a partial hemichrome form. The two alpha-subunit iron atoms are bound to a CO molecule, whereas in the beta subunits the distal histidine residue is the sixth ligand of the heme iron. This structure, a tetrameric hemoglobin in the hemichrome state, demonstrates that the iron coordination by the distal histidine, usually associated with denaturing states, may be tolerated in a native-like hemoglobin structure. In addition, several features of the tertiary and quaternary organization of this structure are intermediate between the R and T states and agree well with the R --> T transition state properties obtained by spectroscopic and kinetic techniques. The analysis of this structure provides a detailed pathway of heme-heme communication and it indicates that the plasticity of the beta heme pocket plays a role in the R --> T transition of tetrameric hemoglobins.

PubMed: 12093902
DOI: 10.1073/pnas.132182099

Experimental method

X-RAY DIFFRACTION (2 Å)