1RQA

Crystallographic Analysis of the Interaction of Nitric Oxide with Quaternary-T Human Hemoglobin. Beta W73E hemoglobin exposed to NO under anaerobic conditions


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.11 Å
  • R-Value Free: 0.231 
  • R-Value Work: 0.188 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Crystallographic analysis of the interaction of nitric oxide with quaternary-T human hemoglobin.

Chan, N.-L.Kavanaugh, J.S.Rogers, P.H.Arnone, A.

(2004) Biochemistry 43: 118-132

  • DOI: 10.1021/bi030172j
  • Primary Citation of Related Structures:  1RPS, 1RQ3, 1RQ4

  • PubMed Abstract: 
  • In addition to interacting with hemoglobin as a heme ligand to form nitrosylhemoglobin, NO can react with cysteine sulfhydryl groups to form S-nitrosocysteine or cysteine oxides such as cysteinesulfenic acid. Both modes of interaction are very sensit ...

    In addition to interacting with hemoglobin as a heme ligand to form nitrosylhemoglobin, NO can react with cysteine sulfhydryl groups to form S-nitrosocysteine or cysteine oxides such as cysteinesulfenic acid. Both modes of interaction are very sensitive to the quaternary structure of hemoglobin. To directly view the interaction of NO with quaternary-T deoxyhemoglobin, crystallographic studies were carried out on crystals of deoxyhemoglobin that were exposed to gaseous NO under a variety of conditions. Consistent with previous spectroscopic studies in solution, these crystallographic studies show that the binding of NO to the heme groups of crystalline wild-type deoxyhemoglobin ruptures the Fe-proximal histidine bonds of the alpha-subunits but not the beta-subunits. This finding supports Perutz's theory that ligand binding induces tension in the alpha Fe-proximal histidine bond. To test Perutz's theory, deoxy crystals of the mutant hemoglobin betaW37E were exposed to NO. This experiment was carried out because previous studies have shown that this mutation greatly reduces the quaternary constraints that oppose the ligand-induced movement of the alpha-heme Fe atom into the plane of the porphyrin ring. As hypothesized, the Fe-proximal histidine bonds in both the beta- and the alpha-subunits remain intact in crystalline betaW37E after exposure to NO. With regard to S-nitrosocysteine or cysteine oxide formation, no evidence for the reaction of NO with any cysteine residues was detected under anaerobic conditions. However, when deoxyhemoglobin crystals are first exposed to air and then to NO, the appearance of additional electron density indicates that Cys93(F9)beta has been modified, most likely to cysteinesulfenic acid. This modification of Cys93(F9)beta disrupts the intrasubunit salt bridge between His146(HC3)beta and Asp94(FG1)beta, a key feature of the quaternary-T hemoglobin structure. Also presented is a reanalysis of our previous crystallographic studies [Chan, N.-L., et al. (1998) Biochemistry 37, 16459-16464] of the interaction of NO with liganded hemoglobin in the quaternary-R2 structure. These studies showed additional electron density at Cys93(F9)beta that was consistent with an NO adduct. However, for reasons discussed in this paper, we now believe that this adduct may be the Hb-S-N.-O-H radical intermediate and not Hb-S-N=O as previously suggested.


    Related Citations: 
    • X-ray Diffraction Studies of Fully Liganded 37beta Mutant Hemoglobins Reveal a T-Like Intermediate Structure with High Ligand Affinity
      Kavanaugh, J.S.,Rogers, P.H.,Arnone, A.
      () TO BE PUBLISHED --: --


    Organizational Affiliation

    Department of Biochemistry, College of Medicine, The University of Iowa, Iowa City, IA 52242, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Hemoglobin alpha chain
A, C
141Homo sapiensGene Names: HBA1, HBA2
Find proteins for P69905 (Homo sapiens)
Go to Gene View: HBA1 HBA2
Go to UniProtKB:  P69905
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Hemoglobin beta chain
B, D
146Homo sapiensGene Names: HBB
Find proteins for P68871 (Homo sapiens)
Go to Gene View: HBB
Go to UniProtKB:  P68871
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
HEM
Query on HEM

Download SDF File 
Download CCD File 
A, B, C, D
PROTOPORPHYRIN IX CONTAINING FE
HEME
C34 H32 Fe N4 O4
KABFMIBPWCXCRK-RGGAHWMASA-L
 Ligand Interaction
NO
Query on NO

Download SDF File 
Download CCD File 
A, B, C, D
NITRIC OXIDE
Nitrogen monoxide
N O
ODUCDPQEXGNKDN-UHFFFAOYAM
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.11 Å
  • R-Value Free: 0.231 
  • R-Value Work: 0.188 
  • Space Group: P 21 21 2
Unit Cell:
Length (Å)Angle (°)
a = 95.300α = 90.00
b = 97.800β = 90.00
c = 66.800γ = 90.00
Software Package:
Software NamePurpose
SDMSdata reduction
X-PLORphasing
REFMACrefinement
SDMSdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2005-01-04
    Type: Initial release
  • Version 1.1: 2008-04-29
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance