Horse Heart Myoglobin, Nitrite Adduct, Co-crystallized

Experimental Data Snapshot

  • Resolution: 1.60 Å
  • R-Value Free: 0.206 
  • R-Value Work: 0.146 
  • R-Value Observed: 0.149 

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Crystal structures of the nitrite and nitric oxide complexes of horse heart myoglobin.

Copeland, D.M.Soares, A.S.West, A.H.Richter-Addo, G.B.

(2006) J Inorg Biochem 100: 1413-1425

  • DOI: https://doi.org/10.1016/j.jinorgbio.2006.04.011
  • Primary Citation of Related Structures:  
    2FRF, 2FRI, 2FRJ, 2FRK

  • PubMed Abstract: 

    Nitrite is an important species in the global nitrogen cycle, and the nitrite reductase enzymes convert nitrite to nitric oxide (NO). Recently, it has been shown that hemoglobin and myoglobin catalyze the reduction of nitrite to NO under hypoxic conditions. We have determined the 1.20 A resolution crystal structure of the nitrite adduct of ferric horse heart myoglobin (hh Mb). The ligand is bound to iron in the nitrito form, and the complex is formulated as MbIII(ONO-). The Fe-ONO bond length is 1.94 A, and the O-N-O angle is 113 degrees . In addition, the nitrite ligand is stabilized by hydrogen bonding with the distal His64 residue. We have also determined the 1.30 A resolution crystal structures of hh MbIINO. When hh MbIINO is prepared from the reaction of metMbIII with nitrite/dithionite, the FeNO angle is 144 degrees with a Fe-NO bond length of 1.87 A. However, when prepared from the reaction of NO with reduced MbII, the FeNO angle is 120 degrees with a Fe-NO bond length of 2.13 A. This difference in FeNO conformations as a function of preparative method is reproducible, and suggests a role of the distal pocket in hh MbIINO in stabilizing local FeNO conformational minima.

  • Organizational Affiliation

    Department of Chemistry and Biochemistry, University of Oklahoma, 620 Parrington Oval, Norman, OK 73019, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
MyoglobinA [auth X]153Equus caballusMutation(s): 0 
Gene Names: MB
Find proteins for P68082 (Equus caballus)
Explore P68082 
Go to UniProtKB:  P68082
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP68082
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.60 Å
  • R-Value Free: 0.206 
  • R-Value Work: 0.146 
  • R-Value Observed: 0.149 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 35.223α = 90
b = 28.592β = 106.03
c = 62.841γ = 90
Software Package:
Software NamePurpose
CrystalCleardata reduction
d*TREKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2006-05-30
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2023-08-30
    Changes: Data collection, Database references, Derived calculations, Refinement description