Cadmium-substituted bovine pancreatic carboxypeptidase A (alfa-form) at pH 7.5 and 2 mM chloride in monoclinic crystal form

Experimental Data Snapshot

  • Resolution: 1.70 Å
  • R-Value Free: 0.198 
  • R-Value Work: 0.174 
  • R-Value Observed: 0.174 

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This is version 1.5 of the entry. See complete history


Three high-resolution crystal structures of cadmium-substituted carboxypeptidase A provide insight into the enzymatic function

Jensen, F.Bukrinsky, T.Bjerrum, J.Larsen, S.

(2002) J Biol Inorg Chem 7: 490-499

  • DOI: https://doi.org/10.1007/s00775-001-0324-0
  • Primary Citation of Related Structures:  
    1EE3, 1ELL, 1ELM

  • PubMed Abstract: 

    Three high-resolution crystal structures of Cd(II)-substituted carboxypeptidase A (CPA) have been determined by X-ray diffraction from crystals prepared in three different buffer systems to assess the effect of pH and ionic strength on the Cd(II) coordination geometry. All crystallize in the space group P2(1) with identical cell dimensions. Cd-CPA(7.5): Cd(II)-substituted CPA prepared at pH 7.5 with [Cl(-)]=2 mM determined to 1.70 A resolution ( R=17.4% and R(free)=19.8%); Cd-CPA(5.5): Cd(II)-substituted CPA prepared at pH 5.5 with [Cl(-)]=2 mM to 2.00 A resolution ( R=16.1% and R(free)=18.6%); Cd-CPA(7.5)-Cl: Cd(II)-substituted CPA prepared at pH 7.5 with [Cl(-)]=250 mM to 1.76 A resolution ( R=16.7% and R(free)=17.8%). No noticeable structural changes were observed between the three structures. Two water molecules coordinate to Cd(II), in contrast to the single water molecule coordinating to Zn(II) in the Zn-CPA structure. No binding sites for anions could be identified, even in the structure with a high concentration of chloride ions. It is suggested that the anion inhibition is due to weak outer-sphere association of Cl(-) ions at several binding sites, shielding the strong positive charge distribution at the surface of the protein near the active site. Based on structural data and a sequence alignment of 18 non-redundant carboxypeptidases, a more elaborate version of the earlier reaction model is proposed that also addresses the transport of water to and from the active site. Conserved residues whose function was not addressed previously delineate the proposed pathways used in the transport of water during catalysis.

  • Organizational Affiliation

    Centre for Crystallographic Studies, Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
PROTEIN (CARBOXYPEPTIDASE A)A [auth P]309Bos taurusMutation(s): 2 
Find proteins for P00730 (Bos taurus)
Explore P00730 
Go to UniProtKB:  P00730
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP00730
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.70 Å
  • R-Value Free: 0.198 
  • R-Value Work: 0.174 
  • R-Value Observed: 0.174 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 47.178α = 90
b = 60.205β = 97.46
c = 51.715γ = 90
Software Package:
Software NamePurpose
SCALEPACKdata scaling
DENZOdata reduction

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2002-06-26
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2017-10-04
    Changes: Refinement description
  • Version 1.4: 2022-12-21
    Changes: Database references, Derived calculations
  • Version 1.5: 2023-09-20
    Changes: Data collection, Refinement description