1YMA

STRUCTURAL CHARACTERIZATION OF HEME LIGATION IN THE HIS64-->TYR VARIANT OF MYOGLOBIN


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

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: 12606-12610


  • PubMed Abstract: 
  • A site-specific mutant of horse heart myoglobin has been prepared in which the distal heme pocket residue, His64, is replaced by tyrosine. The structure of this myoglobin variant has been determined to 2.0-A resolution using x-ray diffraction techniq ...

    A site-specific mutant of horse heart myoglobin has been prepared in which the distal heme pocket residue, His64, is replaced by tyrosine. The structure of this myoglobin variant has been determined to 2.0-A resolution using x-ray diffraction techniques and refined to a final crystallographic R-factor of 16.9%. The polypeptide backbone conformation of the His64-->Tyr variant of myoglobin is very similar to that of the wild-type protein. However, in the variant the water normally found coordinated to the heme iron atom and hydrogen-bonded to His64 has been displaced by the hydroxyl oxygen of the Tyr64 side chain. The tyrosine oxygen atom is directly coordinated to the heme iron atom with a bond length of 2.18 A. Distortion of heme planarity and changes in the packing of the Leu29 and Leu104 side chains are related to this mutation. The ligand environment of the ferric iron has been studied by electron paramagnetic resonance (EPR) spectroscopy using crystalline material and protein in solution. The protein in solution exhibits a rhombically split ferric high spin EPR spectrum with g values of 6.64, 5.34, and 1.98. The EPR spectrum of the crystalline sample consists of two different ferric high spin signals. The main signal is similar to the signal observed in solution and is assigned to His93-Fe(III)-Tyr64 coordination. The relatively high rhombicity of this signal can be explained as arising from distortions of the heme plane seen in the crystal structure. The second, more axial high spin signal found in the crystalline state can be tentatively assigned to another form of iron ligation with a different iron-tyrosine bond length and a less distorted heme plane.


    Related Citations: 
    • Horse Heart Metmyoglobin: A 2.8-Angstroms Resolution Three-Dimensional Structure Determination
      Evans, S.V.,Brayer, G.D.
      (1988) J.Biol.Chem. 263: 4263
    • High-Resolution Study of the Three-Dimensional Structure of Horse Heart Metmyoglobin
      Evans, S.V.,Brayer, G.D.
      (1990) J.Mol.Biol. 213: 885
    • 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: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
MYOGLOBIN
A
153Equus caballusMutation(s): 0 
Gene Names: MB
Find proteins for P68082 (Equus caballus)
Go to Gene View: MB
Go to UniProtKB:  P68082
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
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 63.700α = 90.00
b = 28.800β = 106.60
c = 35.700γ = 90.00
Software Package:
Software NamePurpose
PROLSQrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1994-01-31
    Type: Initial release
  • Version 1.1: 2008-03-24
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2017-11-29
    Type: Derived calculations, Other