Structure of mammalian cytochrome P450 2B4

Experimental Data Snapshot

  • Resolution: 1.60 Å
  • R-Value Free: 0.289 
  • R-Value Observed: 0.217 

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An open conformation of mammalian cytochrome P450 2B4 at 1.6 A resolution

Scott, E.E.He, Y.A.Wester, M.R.White, M.A.Chin, C.C.Halpert, J.R.Johnson, E.F.Stout, C.D.

(2003) Proc Natl Acad Sci U S A 100: 13196-13201

  • DOI: https://doi.org/10.1073/pnas.2133986100
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    The xenobiotic metabolizing cytochromes P450 (P450s) are among the most versatile biological catalysts known, but knowledge of the structural basis for their broad substrate specificity has been limited. P450 2B4 has been frequently used as an experimental model for biochemical and biophysical studies of these membrane proteins. A 1.6-A crystal structure of P450 2B4 reveals a large open cleft that extends from the protein surface directly to the heme iron between the alpha-helical and beta-sheet domains without perturbing the overall P450 fold. This cleft is primarily formed by helices B' to C and F to G. The conformation of these regions is dramatically different from that of the other structurally defined mammalian P450, 2C5/3LVdH, in which the F to G and B' to C regions encapsulate one side of the active site to produce a closed form of the enzyme. The open conformation of 2B4 is trapped by reversible formation of a homodimer in which the residues between helices F and G of one molecule partially fill the open cleft of a symmetry-related molecule, and an intermolecular coordinate bond occurs between H226 and the heme iron. This dimer is observed both in solution and in the crystal. Differences between the structures of 2C5 and 2B4 suggest that defined regions of xenobiotic metabolizing P450s may adopt a substantial range of energetically accessible conformations without perturbing the overall fold. This conformational flexibility is likely to facilitate substrate access, metabolic versatility, and product egress.

  • Organizational Affiliation

    Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555-1031, USA. eescott@x-ray.utmb.edu

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Cytochrome P450 2B4476Oryctolagus cuniculusMutation(s): 8 
Gene Names: 2B4
Membrane Entity: Yes 
Find proteins for P00178 (Oryctolagus cuniculus)
Explore P00178 
Go to UniProtKB:  P00178
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP00178
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on HEM

Download Ideal Coordinates CCD File 
C34 H32 Fe N4 O4
Experimental Data & Validation

Experimental Data

  • Resolution: 1.60 Å
  • R-Value Free: 0.289 
  • R-Value Observed: 0.217 
  • Space Group: C 2 2 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 57.09α = 90
b = 114.2β = 90
c = 133.95γ = 90
Software Package:
Software NamePurpose
MOSFLMdata reduction
SCALAdata scaling
CCP4model building
CCP4data scaling

Structure Validation

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Ligand Structure Quality Assessment 

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2003-10-07
    Type: Initial release
  • Version 1.1: 2008-04-29
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Version format compliance
  • Version 1.3: 2021-10-27
    Changes: Database references, Derived calculations
  • Version 1.4: 2023-08-16
    Changes: Data collection, Refinement description