1CMT

THE ROLE OF ASPARTATE-235 IN THE BINDING OF CATIONS TO AN ARTIFICIAL CAVITY AT THE RADICAL SITE OF CYTOCHROME C PEROXIDASE


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.10 Å
  • R-Value Work: 0.168 
  • R-Value Observed: 0.168 

wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

The role of aspartate-235 in the binding of cations to an artificial cavity at the radical site of cytochrome c peroxidase.

Fitzgerald, M.M.Trester, M.L.Jensen, G.M.McRee, D.E.Goodin, D.B.

(1995) Protein Sci 4: 1844-1850

  • DOI: 10.1002/pro.5560040919
  • Primary Citation of Related Structures:  
    1CMU, 1CMT

  • PubMed Abstract: 
  • The activated state of cytochrome c peroxidase, compound ES, contains a cation radical on the Trp-191 side chain. We recently reported that replacing this tryptophan with glycine creates a buried cavity at the active site that contains ordered solvent and that will specifically bind substituted imidazoles in their protonated cationic forms (Fitzgerald MM, Churchill MJ, McRee DE, Goodin DB, 1994, Biochemistry 33:3807-3818) ...

    The activated state of cytochrome c peroxidase, compound ES, contains a cation radical on the Trp-191 side chain. We recently reported that replacing this tryptophan with glycine creates a buried cavity at the active site that contains ordered solvent and that will specifically bind substituted imidazoles in their protonated cationic forms (Fitzgerald MM, Churchill MJ, McRee DE, Goodin DB, 1994, Biochemistry 33:3807-3818). Proposals that a nearby carboxylate, Asp-235, and competing monovalent cations should modulate the affinity of the W191G cavity for ligand binding are addressed in this study. Competitive binding titrations of the imidazolium ion to W191G as a function of [K+] show that potassium competes weakly with the binding of imidazoles. The dissociation constant observed for potassium binding (18 mM) is more than 3,000-fold higher than that for 1,2-dimethylimidazole (5.5 microM) in the absence of competing cations. Significantly, the W191G-D235N double mutant shows no evidence for binding imidazoles in their cationic or neutral forms, even though the structure of the cavity remains largely unperturbed by replacement of the carboxylate. Refined crystallographic B-values of solvent positions indicate that the weakly bound potassium in W191G is significantly depopulated in the double mutant. These results demonstrate that the buried negative charge of Asp-235 is an essential feature of the cation binding determinant and indicate that this carboxylate plays a critical role in stabilizing the formation of the Trp-191 radical cation.


    Related Citations: 
    • 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
    • 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, Scripps Research Institute, La Jolla, California 92037, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
CYTOCHROME C PEROXIDASEA294Saccharomyces cerevisiaeMutation(s): 0 
EC: 1.11.1.5
UniProt
Find proteins for P00431 (Saccharomyces cerevisiae (strain ATCC 204508 / S288c))
Explore P00431 
Go to UniProtKB:  P00431
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
HEM
Query on HEM

Download Ideal Coordinates CCD File 
B [auth A]PROTOPORPHYRIN IX CONTAINING FE
C34 H32 Fe N4 O4
KABFMIBPWCXCRK-RGGAHWMASA-L
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.10 Å
  • R-Value Work: 0.168 
  • R-Value Observed: 0.168 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 108α = 90
b = 77.3β = 90
c = 51.8γ = 90
Software Package:
Software NamePurpose
X-PLORmodel building
X-PLORrefinement
X-PLORphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1995-07-10
    Type: Initial release
  • Version 1.1: 2008-03-24
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2017-11-29
    Changes: Derived calculations, Other