3ARK: Cl- Binding Hemoglobin Component V Form Propsilocerus Akamusi Under 1 M Nacl At Ph 4.6

Monomeric haemoglobin component V (Hb V) from the larva of the midge Propsilocerus akamusi shows high Cl affinity under high salt concentrations at acidic pH. In order to understand the structural changes that depend on Cl binding, crystal structures of Hb V were determined under acidic high-salt conditions and the structural changes arising from different haem-bound ligands were simulated. Crystal structures of Hb V under acidic high-salt conditions indicated that the side chain of ArgE10 on the distal face of the haem contributes to stabilizing haem-bound Cl. The conformation of the Arg side chain in the Cl-bound form was almost identical to that in ligated Hb V at neutral pH but not to that in met Hb V under acidic salt-free conditions. Furthermore, preliminary molecular-dynamics simulations also indicated that the swinging of the Arg side chain into the haem pocket depends on Cl ligation. This result suggests that, like pH change, Cl binding affects the location of the distal Arg residue. Owing to the increased positive electrostatic potential observed in the haem pocket at acidic pH, it was concluded that electrostatic changes caused by pH change and anionic ligand binding may affect the behaviour of the polar Arg residue.
PDB ID: 3ARKDownload
MMDB ID: 90117
PDB Deposition Date: 2010/12/2
Updated in MMDB: 2011/05
Experimental Method:
x-ray diffraction
Resolution: 1.81  Å
Source Organism:
Similar Structures:
Biological Unit for 3ARK: monomeric; determined by author and by software (PISA)
Molecular Components in 3ARK
Label Count Molecule
Protein (1 molecule)
Hemoglobin V
Molecule annotation
Chemicals (6 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB