1HSY

ORIGIN OF THE PH-DEPENDENT SPECTROSCOPIC PROPERTIES OF PENTACOORDINATE METMYOGLOBIN VARIANTS


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.90 Å
  • R-Value Observed: 0.163 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Origin of the pH-dependent spectroscopic properties of pentacoordinate metmyoglobin variants.

Bogumil, R.Maurus, R.Hildebrand, D.P.Brayer, G.D.Mauk, A.G.

(1995) Biochemistry 34: 10483-10490

  • DOI: 10.1021/bi00033a021
  • Primary Citation of Related Structures:  
    1HSY

  • PubMed Abstract: 
  • The pH dependence of the electronic and EPR spectra of two variants of horse heart myoglobin (Mb) in which the distal His64 ligand has been replaced by either Thr or Ile has been studied. Both of these variants exhibit spectroscopic changes with pH t ...

    The pH dependence of the electronic and EPR spectra of two variants of horse heart myoglobin (Mb) in which the distal His64 ligand has been replaced by either Thr or Ile has been studied. Both of these variants exhibit spectroscopic changes with pH that are indicative of a transition between two ferric high-spin forms that occurs with a pKa of 9.49 for the His64Thr variant and 9.26 for the His64Ile variant and that is distinctly different from the pH-dependent spectroscopic changes related to titration of the distal aquo ligand of wild-type Mb. The electronic and EPR spectra of both variants at all values of pH studied are consistent with the presence of a pentacoordinate heme iron center. For the His64Thr variant, a high-resolution (1.9 A) structure determination establishes the lack of the distal aquo ligand and demonstrates an out-of-plane movement of the ferric iron toward the proximal histidine together with a decrease of the Fe-His bond length. Investigation of this pH-linked equilibrium by EPR spectroscopy reveals rhombically split high-spin signals at both pH 7 and 11 with a greater degree of rhombicity exhibited by the alkaline species. We propose that the pH-linked spectroscopic transition exhibited by these distal histidine variants results from the deprotonation of the proximal His93 residue to produce imidazolate ligation at alkaline pH.


    Related Citations: 
    • Thermal Destabilization of Horse Heart Myoglobin Through Modification of a Hydrophobic Cluster in the Proximal Heme Pocket
      Maurus, R., Overall, C.M., Bogumil, R., Luo, Y., Mauk, A.G., Smith, M., Brayer, G.D.
      () To be published --: --
    • Structural Characterization of Heme Ligation in the His64->Tyr Variant of Myoglobin
      Maurus, R., Bogumil, R., Luo, Y., Tang, H.L., Smith, M., Mauk, A.G., Brayer, G.D.
      (1994) J Biol Chem 269: 12606
    • Ftir Analysis of the Interaction of Azide with Horse Heart Myoglobin
      Bogumil, R., Hunter, C.L., Maurus, R., Tang, H.L., Lee, H., Lloyd, E., Brayer, G.D., Smith, M., Mauk, A.G.
      (1994) Biochemistry 33: 7600
    • Three-Dimensional Structure of Cyanomet-Sulfmyoglobin C
      Evans, S.V., Sishta, B.P., Mauk, A.G., Brayer, G.D.
      (1994) Proc Natl Acad Sci U S A 91: 4723
    • Expression in Escherichia Coli of a Synthetic Gene Coding for Horse Heart Myoglobin
      Guillemette, J.G., Matsushima-Hibiya, Y., Atkinson, T., Smith, M.
      (1991) Protein Eng 4: 585
    • High-Resolution Study of the Three-Dimensional Structure of Horse Heart Myoglobin
      Evans, S.V., Brayer, G.D.
      (1990) J Mol Biol 213: 885
    • Horse Heart Metmyoglobin: A 2.8-Angstroms Resolution Three-Dimensional Structure Determination
      Evans, S.V., Brayer, G.D.
      (1988) J Biol Chem 263: 4263
    • Crystallization and Preliminary Diffraction Data for Horse Heart Metmyoglobin
      Sherwood, C., Mauk, A.G., Brayer, G.D.
      (1987) J Mol Biol 193: 227

    Organizational Affiliation

    Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
MYOGLOBINA153Equus caballusMutation(s): 0 
Gene Names: SYNTHETIC GENEMB
Find proteins for P68082 (Equus caballus)
Explore P68082 
Go to UniProtKB:  P68082
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
HEM
Query on HEM

Download Ideal Coordinates CCD File 
A
PROTOPORPHYRIN IX CONTAINING FE
C34 H32 Fe N4 O4
KABFMIBPWCXCRK-RGGAHWMASA-L
 Ligand Interaction
SO4
Query on SO4

Download Ideal Coordinates CCD File 
A
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.90 Å
  • R-Value Observed: 0.163 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 64.403α = 90
b = 28.856β = 107.2
c = 35.79γ = 90
Software Package:
Software NamePurpose
PROLSQrefinement

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1995-02-27
    Type: Initial release
  • Version 1.1: 2008-03-24
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance