F393A mutant heme domain of flavocytochrome P450 BM3

Experimental Data Snapshot

  • Resolution: 2.05 Å
  • R-Value Free: 0.237 
  • R-Value Work: 0.169 

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This is version 1.4 of the entry. See complete history


Oxygen Activation and Electron Transfer in Flavocytochrome P450 BM3

Ost, T.W.B.Clark, J.Mowat, C.G.Miles, C.S.Walkinshaw, M.D.Reid, G.A.Chapman, S.K.Daff, S.

(2003) J Am Chem Soc 125: 15010-15020

  • DOI: https://doi.org/10.1021/ja035731o
  • Primary Citation of Related Structures:  
    1P0V, 1P0W, 1P0X

  • PubMed Abstract: 

    In flavocytochrome P450 BM3, there is a conserved phenylalanine residue at position 393 (Phe393), close to Cys400, the thiolate ligand to the heme. Substitution of Phe393 by Ala, His, Tyr, and Trp has allowed us to modulate the reduction potential of the heme, while retaining the structural integrity of the enzyme's active site. Substrate binding triggers electron transfer in P450 BM3 by inducing a shift from a low- to high-spin ferric heme and a 140 mV increase in the heme reduction potential. Kinetic analysis of the mutants indicated that the spin-state shift alone accelerates the rate of heme reduction (the rate determining step for overall catalysis) by 200-fold and that the concomitant shift in reduction potential is only responsible for a modest 2-fold rate enhancement. The second step in the P450 catalytic cycle involves binding of dioxygen to the ferrous heme. The stabilities of the oxy-ferrous complexes in the mutant enzymes were also analyzed using stopped-flow kinetics. These were found to be surprisingly stable, decaying to superoxide and ferric heme at rates of 0.01-0.5 s(-)(1). The stability of the oxy-ferrous complexes was greater for mutants with higher reduction potentials, which had lower catalytic turnover rates but faster heme reduction rates. The catalytic rate-determining step of these enzymes can no longer be the initial heme reduction event but is likely to be either reduction of the stabilized oxy-ferrous complex, i.e., the second flavin to heme electron transfer or a subsequent protonation event. Modulating the reduction potential of P450 BM3 appears to tune the two steps in opposite directions; the potential of the wild-type enzyme appears to be optimized to maximize the overall rate of turnover. The dependence of the visible absorption spectrum of the oxy-ferrous complex on the heme reduction potential is also discussed.

  • Organizational Affiliation

    School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JJ. Simon.Daff@ed.ac.uk

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Bifunctional P-450:NADPH-P450 reductase
A, B
455Priestia megateriumMutation(s): 1 
Gene Names: CYP102A21
Find proteins for P14779 (Priestia megaterium (strain ATCC 14581 / DSM 32 / CCUG 1817 / JCM 2506 / NBRC 15308 / NCIMB 9376 / NCTC 10342 / NRRL B-14308 / VKM B-512 / Ford 19))
Explore P14779 
Go to UniProtKB:  P14779
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP14779
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on HEM

Download Ideal Coordinates CCD File 
C [auth A],
D [auth B]
C34 H32 Fe N4 O4
Experimental Data & Validation

Experimental Data

  • Resolution: 2.05 Å
  • R-Value Free: 0.237 
  • R-Value Work: 0.169 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 58.694α = 90
b = 152.911β = 94.64
c = 61.197γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

View Full Validation Report

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2003-12-09
    Type: Initial release
  • Version 1.1: 2008-04-29
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2021-10-27
    Changes: Data collection, Database references, Derived calculations
  • Version 1.4: 2023-08-16
    Changes: Data collection, Refinement description