Experimental Data Snapshot

  • Resolution: 2.20 Å
  • R-Value Work: 0.193 
  • R-Value Observed: 0.193 

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Crystal structure of recombinant pea cytosolic ascorbate peroxidase.

Patterson, W.R.Poulos, T.L.

(1995) Biochemistry 34: 4331-4341

  • DOI: https://doi.org/10.1021/bi00013a023
  • Primary Citation of Related Structures:  
    1APX, 1CCK

  • PubMed Abstract: 

    The crystal structure of recombinant pea cytosolic ascorbate peroxidase has been refined to an R = 0.19 for data between 8.0 and 2.2 A resolution and magnitude of F > or = 2 sigma(magnitude of F). The refined model consists of four ascorbate peroxidase monomers consisting of 249 residues per monomer assembled into two homodimers, with one heme group per monomer. The ascorbate peroxidase model confirms that the pea cytosolic enzyme is a noncovalent homodimer held together by a series of ionic interactions arranged around the 2-fold noncrystallographic dimer axis. As expected from the high level of sequence identity (33%), the overall fold of the ascorbate peroxidase monomer closely resembles that of cytochrome c peroxidase. The average root mean square differences for 137 helical alpha-carbon atoms between the four ascorbate peroxidase monomers and cytochrome c peroxidase and for 249 topologically equivalent alpha-carbon atoms are 0.9 and 1.3 A, respectively. The active site structures are also the same, including the hydrogen-bonding interactions between the proximal His ligand, a buried Asp residue, and a Trp residue, whose indole ring is parallel to and in contact with the proximal His ligand just under the heme ring. This proximal Trp residue is thought to be the site of free radical formation in cytochrome c peroxidase compound I and is also essential for enzyme activity. The corresponding Trp in ascorbate peroxidase, Trp179, occupies exactly the same position. The most interesting, and possibly functionally important, difference between the two peroxidases is the presence of a cation binding site in ascorbate peroxidase located approximately 8 A from the alpha-carbon atom of Trp179.

  • Organizational Affiliation

    Department of Physiology and Biophysics, University of California, Irvine 92717, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B, C, D
249Pisum sativumMutation(s): 0 
Gene Names: CDNA
Find proteins for P48534 (Pisum sativum)
Explore P48534 
Go to UniProtKB:  P48534
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP48534
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.20 Å
  • R-Value Work: 0.193 
  • R-Value Observed: 0.193 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 132.4α = 90
b = 53β = 107.1
c = 170.6γ = 90
Software Package:
Software NamePurpose
X-PLORmodel building
XENGENdata reduction

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1996-03-08
    Type: Initial release
  • Version 1.1: 2008-03-03
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2017-11-29
    Changes: Derived calculations, Other
  • Version 1.4: 2024-02-07
    Changes: Data collection, Database references, Derived calculations