1AEV

INTRODUCTION OF NOVEL SUBSTRATE OXIDATION INTO CYTOCHROME C PEROXIDASE BY CAVITY COMPLEMENTATION: OXIDATION OF 2-AMINOTHIAZOLE AND COVALENT MODIFICATION OF THE ENZYME (2-AMINOTHIAZOLE)


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.1 Å

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Introduction of novel substrate oxidation into cytochrome c peroxidase by cavity complementation: oxidation of 2-aminothiazole and covalent modification of the enzyme.

Musah, R.A.Goodin, D.B.

(1997) Biochemistry 36: 11665-11674

  • DOI: 10.1021/bi9708038

  • PubMed Abstract: 
  • The binding and oxidation of an artificial substrate, 2-aminothiazole, by an engineered cavity of cytochrome c peroxidase is described. The W191G mutant has been shown to create a buried cavity into which a number of small heterocyclic compounds will ...

    The binding and oxidation of an artificial substrate, 2-aminothiazole, by an engineered cavity of cytochrome c peroxidase is described. The W191G mutant has been shown to create a buried cavity into which a number of small heterocyclic compounds will bind [Fitzgerald, M. M., Churchill, M. J., McRee, D. E., & Goodin, D. B. (1994) Biochemistry 33, 3807-3818], providing a specific site near the heme from which substrates might be oxidized. In this study, we show by titration calorimetry that 2-aminothiazole binds to W191G with a Kd of 0.028 mM at pH 6. A crystal structure at 2.3 A resolution of W191G in the presence of 2-aminothiazole reveals the occupation of this compound in the cavity, and indicates that it is in van der Waals contact with the heme. The WT enzyme reacts with H2O2 to form Compound ES, in which both the iron center and the Trp-191 side chain are reversibly oxidized. For the W191F (and perhaps the W191G) mutants, the iron is still oxidized, but the second equivalent exists transiently as a radical on the porphyrin before migrating to an alternate protein radical site [Erman, J. E., Vitello, L. B., Mauro, J. M., & Kraut, J. (1989) Biochemistry 28, 7992-7995]. Two separate reactions are observed between 2-aminothiazole and the oxidized centers of W191G. In the one reaction, optical and EPR spectra of the heme are used to show that 2-aminothiazole acts as an electron donor to the ferryl (Fe4+&dbd;O) center of W191G to reduce it to the ferric oxidation state. This reaction occurs from within the cavity, as it is not observed for variants that lack this artificial binding site. A second reaction between 2-aminothiazole and peroxide-oxidized W191G, which is much less efficient, results in the specific covalent modification of Tyr-236. Electrospray mass spectra of the W191G after incubation in 2-aminothiazole and H2O2 show a modification of the protein indicative of covalent binding of 2-aminothiazole. The site of modification was determined to be Tyr-236 by CNBr peptide mapping and automated peptide sequencing. The covalent modification is only observed for W191G and W191F which form the alternate radical center. This observation provides an unanticipated assignment of this free radical species to Tyr-236, which is consistent with previous proposals that it is a tyrosine. The oxidation of 2-aminothiazole by W191G represents an example of how the oxidative capacity inherent in the heme prosthetic group and the specific binding behavior of artificial protein cavities can be harnessed and redirected toward the oxidation of organic substrates.


    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
    • Small Molecule Binding to an Artificially Created Cavity at the Active Site of Cytochrome C Peroxidase
      Fitzgerald, M.M.,Churchill, M.J.,Mcree, D.E.,Goodin, D.B.
      (1994) Biochemistry 33: 3807


    Organizational Affiliation

    Department of Molecular Biology, MB8, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
CYTOCHROME C PEROXIDASE
A
294Saccharomyces cerevisiae (strain ATCC 204508 / S288c)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 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
AMT
Query on AMT

Download SDF File 
Download CCD File 
A
2-AMINOTHIAZOLE
C3 H4 N2 S
RAIPHJJURHTUIC-UHFFFAOYSA-N
 Ligand Interaction
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: 2.1 Å
  • 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
XENGENdata scaling
XTALVIEWrefinement
XENGENdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1997-09-04
    Type: Initial release
  • Version 1.1: 2008-03-24
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance