1TES

OXYGEN BINDING MUSCLE PROTEIN


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.70 Å
  • R-Value Work: 0.159 
  • R-Value Observed: 0.159 

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This is version 1.2 of the entry. See complete history


Literature

Mechanism of NO-induced oxidation of myoglobin and hemoglobin.

Eich, R.F.Li, T.Lemon, D.D.Doherty, D.H.Curry, S.R.Aitken, J.F.Mathews, A.J.Johnson, K.A.Smith, R.D.Phillips Jr., G.N.Olson, J.S.

(1996) Biochemistry 35: 6976-6983

  • DOI: 10.1021/bi960442g
  • Primary Citation of Related Structures:  
    1TES

  • PubMed Abstract: 
  • Nitric oxide (NO) has been implicated as mediator in a variety of physiological functions, including neurotransmission, platelet aggregation, macrophage function, and vasodilation. The consumption of NO by extracellular hemoglobin and subsequent vasoconstriction have been suggested to be the cause of the mild hypertensive events reported during in vivo trials of hemoglobin-based O2 carriers ...

    Nitric oxide (NO) has been implicated as mediator in a variety of physiological functions, including neurotransmission, platelet aggregation, macrophage function, and vasodilation. The consumption of NO by extracellular hemoglobin and subsequent vasoconstriction have been suggested to be the cause of the mild hypertensive events reported during in vivo trials of hemoglobin-based O2 carriers. The depletion of NO from endothelial cells is most likely due to the oxidative reaction of NO with oxyhemoglobin in arterioles and surrounding tissue. In order to determine the mechanism of this key reaction, we have measured the kinetics of NO-induced oxidation of a variety of different recombinant sperm whale myoglobins (Mb) and human hemoglobins (Hb). The observed rates depend linearly on [NO] but show no dependence on [O2]. The bimolecular rate constants for NO-induced oxidation of MbO2 and HbO2 are large (k.ox,NO = 30-50 microM-1 s-1 for the wild-type proteins) and similar to those for simple nitric oxide binding to deoxygenated Mb and Hb. Both reversible NO binding and NO-induced oxidation occur in two steps: (1) bimolecular entry of nitric oxide into the distal portion of the heme pocket and (2) rapid reaction of noncovalently bound nitric oxide with the iron atom to produce Fe(2+)-N=O or with Fe(2+)-O-O delta- to produce Fe(3+)-OH2 and nitrate. Both the oxidation and binding rate constants for sperm whale Mb were increased when His(E7) was replaced by aliphatic residues. These mutants lack polar interactions in the distal pocket which normally hinder NO entry into the protein. Decreasing the volume of the distal pocket by replacing Leu(B10) and Val(E11) with aromatic amino acids markedly inhibits NO-induced oxidation of MbO2. The latter results provide a protein engineering strategy for reducing hypertensive events caused by extracellular hemoglobin-based O2 carriers. This approach has been explored by examining the effects of Phe(B10) and Phe(E11) substitutions on the rates of NO-induced oxidation of the alpha and beta subunits in recombinant human hemoglobin.


    Organizational Affiliation

    Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005-1892, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
MYOGLOBINA154Physeter catodonMutation(s): 0 
Gene Names: MB
UniProt
Find proteins for P02185 (Physeter macrocephalus)
Explore P02185 
Go to UniProtKB:  P02185
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
HEM (Subject of Investigation/LOI)
Query on HEM

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

Download Ideal Coordinates CCD File 
B [auth A]SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
ETN
Query on ETN

Download Ideal Coordinates CCD File 
D [auth A]METHYLETHYLAMINE
C3 H9 N
LIWAQLJGPBVORC-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.70 Å
  • R-Value Work: 0.159 
  • R-Value Observed: 0.159 
  • Space Group: P 6
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 91.622α = 90
b = 91.622β = 90
c = 45.963γ = 120
Software Package:
Software NamePurpose
X-PLORmodel building
X-PLORrefinement
R-AXISdata reduction
R-AXISdata scaling
X-PLORphasing

Structure Validation

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Ligand Structure Quality Assessment  



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1996-11-08
    Type: Initial release
  • Version 1.1: 2008-03-24
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance