1VXA

NATIVE SPERM WHALE MYOGLOBIN


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å
  • R-Value Work: 0.177 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Crystal structures of CO-, deoxy- and met-myoglobins at various pH values.

Yang, F.Phillips Jr., G.N.

(1996) J.Mol.Biol. 256: 762-774

  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • The distal histidine residue, His64(E7), and the proximal histidine residue, His93(F8), in myoglobin (Mb) are important for the function of the protein. For example, the increase in the association rate constant for CO binding at low pH has been sugg ...

    The distal histidine residue, His64(E7), and the proximal histidine residue, His93(F8), in myoglobin (Mb) are important for the function of the protein. For example, the increase in the association rate constant for CO binding at low pH has been suggested to be caused by the protonation of these histidine residues. In order to investigate the influence of protonation on the structure of myoglobin, we determined the crystal structures of sperm whale myoglobin to 2.0 A or better in different states of ligation (MbCO, deoxyMb and metMb) at pH values of 4, 5 and 6. The most dramatic change found at low pH is that His64 swings out of the distal pocket in the MbCO structure at pH 4, opening a direct channel from the solvent to the iron atom. This rotation seems to be facilitated by conformational changes in the CD corner. The benzyl side-chain of Phe46(CD4), which has been suggested to be a critical residue in controlling the rotation of His64, moves away from His64 at pH 4 in the deoxyMb structure, allowing more free rotation of His64. Arg45(CD3) is also important for the dynamics of myoglobin, since it influences the pK(a) of His64 and forms a hydrogen bond lattice that hinders the rotation of His64 at neutral pH. This hydrogen-bond lattice disappears at low pH. Although His64 rotates out of the distal pocket in the MbCO structure at pH 4, leaving more space for the CO ligand, the Fe-C-O angle refines to about 130 degrees, the same as those at pH 5 and 6. In the MbCO structure at pH 4, significant conformational changes appear in the EF corner. The peptide plane between Lys79(EF2) and Gly80(EF3) flips about 150 degrees. The occupancy of this conformation in the MbCO structures increases with decreases in pH. On the proximal side of the heme, the bond between the heme iron atom and N(epsilon) of His93 remains intact under the experimental conditions in the MbCO and deoxyMb structures, but appears elongated in the metMb structure at pH 4, representing either a weakened bond or the breakage of the bond in some fraction of the molecules in the crystal.


    Related Citations: 
    • X-Ray Structure and Refinement of Carbon-Monoxy (Fe II)-Myoglobin at 1.5 A Resolution
      Kuriyan, J.,Wilz, S.,Karplus, M.,Petsko, G.A.
      (1986) J.Mol.Biol. 192: 133


    Organizational Affiliation

    The W.M. Keck Center for Computational Biology, Rice University, Houston, TX 77005-1892, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
MYOGLOBIN
A
153Physeter macrocephalusMutation(s): 0 
Gene Names: MB
Find proteins for P02185 (Physeter macrocephalus)
Go to Gene View: MB
Go to UniProtKB:  P02185
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SO4
Query on SO4

Download SDF File 
Download CCD File 
A
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
HEM
Query on HEM

Download SDF File 
Download CCD File 
A
PROTOPORPHYRIN IX CONTAINING FE
HEME
C34 H32 Fe N4 O4
KABFMIBPWCXCRK-RGGAHWMASA-L
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å
  • R-Value Work: 0.177 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 64.652α = 90.00
b = 30.832β = 106.30
c = 35.088γ = 90.00
Software Package:
Software NamePurpose
XDSdata reduction
X-PLORrefinement
X-PLORmodel building
X-PLORphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1996-08-01
    Type: Initial release
  • Version 1.1: 2008-03-24
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance