3CCX

ALTERING SUBSTRATE SPECIFICITY AT THE HEME EDGE OF CYTOCHROME C PEROXIDASE


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.3 Å
  • R-Value Work: 0.170 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

Altering substrate specificity at the heme edge of cytochrome c peroxidase.

Wilcox, S.K.Jensen, G.M.Fitzgerald, M.M.McRee, D.E.Goodin, D.B.

(1996) Biochemistry 35: 4858-4866

  • DOI: 10.1021/bi952929f
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Two mutants of cytochrome c peroxidase (CCP) are reported which exhibit unique specificities toward oxidation of small substrates. Ala-147 in CCP is located near the delta-meso edge of the heme and along the solvent access channel through which H2O2 ...

    Two mutants of cytochrome c peroxidase (CCP) are reported which exhibit unique specificities toward oxidation of small substrates. Ala-147 in CCP is located near the delta-meso edge of the heme and along the solvent access channel through which H2O2 is thought to approach the active site. This residue was replaced with Met and Tyr to investigate the hypothesis that small molecule substrates are oxidized at the exposed delta-meso edge of the heme. X-ray crystallographic analyses confirm that the side chains of A147M and A147Y are positioned over the delta-meso heme position and might therefore modify small molecule access to the oxidized heme cofactor. Steady-state kinetic measurements show that cytochrome c oxidation is enhanced 3-fold for A147Y relative to wild type, while small molecule oxidation is altered to varying degrees depending on the substrate and mutant. For example, oxidation of phenols by A147Y is reduced to less than 20% relative to the wild-type enzyme, while Vmax/e for oxidation of other small molecules is less affected by either mutation. However, the "specificity" of aniline oxidation by A147M, i.e., (Vmax/e)/Km, is 43-fold higher than in wild-type enzyme, suggesting that a specific interaction for aniline has been introduced by the mutation. Stopped-flow kinetic data show that the restricted heme access in A147Y or A147M slows the reaction between the enzyme and H202, but not to an extent that it becomes rate limiting for the oxidation of the substrates examined. The rate constant for compound ES formation with A147Y is 2.5 times slower than wild-type CCP. These observations strongly support the suggestion that small molecule oxidations occur at sites on the enzyme distinct from those utilized by cytochrome c and that the specificity of small molecule oxidation can be significantly modulated by manipulating access to the heme edge. The results help to define the role of alternative electron transfer pathways in cytochrome c peroxidase and may have useful applications in improving the specificity of peroxidase with engineered function.


    Related Citations: 
    • The Asp-His-Fe Triad of Cytochrome C Peroxidase Controls the Reduction Potential, Electronic Structure and Coupling of the Tryptophan Free-Radical to the Heme
      Goodin, D.B.,Mcree, D.E.
      (1993) Biochemistry 32: 3313


    Organizational Affiliation

    Department of Molecular Biology, The Scripps Research Institute, La Jolla, Calfornia 92037, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
CYTOCHROME C PEROXIDASE
A
294Saccharomyces cerevisiae (strain ATCC 204508 / S288c)Mutation(s): 0 
Gene Names: CCP1 (CCP, CPO)
EC: 1.11.1.5
Find proteins for P00431 (Saccharomyces cerevisiae (strain ATCC 204508 / S288c))
Go to UniProtKB:  P00431
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
HEM
Query on HEM

Download SDF File 
Download CCD File 
A
PROTOPORPHYRIN IX CONTAINING FE
HEME
C34 H32 Fe N4 O4
KABFMIBPWCXCRK-RGGAHWMASA-L
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.3 Å
  • R-Value Work: 0.170 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 105.200α = 90.00
b = 74.300β = 90.00
c = 45.400γ = 90.00
Software Package:
Software NamePurpose
X-PLORrefinement
X-PLORmodel building
X-PLORphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1995-07-10
    Type: Initial release
  • Version 1.1: 2008-03-25
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2017-11-29
    Type: Advisory, Derived calculations, Other