1K2I

Crystal Structure of Gamma-Chymotrypsin in Complex with 7-Hydroxycoumarin


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.200 
  • R-Value Work: 0.180 
  • R-Value Observed: 0.190 

Starting Model: experimental
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This is version 1.3 of the entry. See complete history


Literature

Crystal structure of gamma-chymotrypsin in complex with 7-hydroxycoumarin.

Ghani, U.Ng, K.K.Atta-ur-RahmanChoudhary, M.I.Ullah, N.James, M.N.

(2001) J Mol Biol 314: 519-525

  • DOI: https://doi.org/10.1006/jmbi.2001.5148
  • Primary Citation of Related Structures:  
    1K2I

  • PubMed Abstract: 

    The 1.8 A crystal structure of 7-hydroxycoumarin (7-HC) bound to chymotrypsin reveals that this inhibitor forms a planar cinnamate acyl-enzyme complex. The phenyl ring of the bound inhibitor forms numerous van der Waals contacts in the S1 pocket of the enzyme, with the p-hydroxyl group donating a hydrogen bond to the main-chain oxygen atom of Ser217, and the o-hydroxyl group forming a water-mediated hydrogen bond with the carbonyl oxygen of Val227. The structure of the acyl-enzyme complex suggests that the mechanism of inhibition of 7-HC involves nucleophilic attack by the Ser195 O(gamma) atom on the carbonyl carbon atom of the inhibitor, accompanied by the breaking of the 2-pyrone ring of the inhibitor, and leading to the formation of a cinnamate acyl-enzyme derivative via a tetrahedral transition state. Comparisons with structures of photoreversible cinnamates bound to chymotrypsin reveal that although 7-HC interacts with the enzyme in a similar fashion, the binding of 7-HC to chymotrypsin takes place in a productive conformation in contrast to the photoreversible cinnamates. In summary, the 7-HC-chymotrypsin complex provides basic insight into the inhibition of chymotrypsin by natural coumarins and provides a structural basis for the design of more potent mechanism-based inhibitors against a wide range of biologically important chymotrypsin-like enzymes.


  • Organizational Affiliation

    International Centre for Chemical Sciences, H. E. J. Research Institute of Chemistry, University of Karachi, Karachi, 75270, Pakistan.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
CHYMOTRYPSINOGEN AA [auth 1]245Bos taurusMutation(s): 0 
EC: 3.4.21.1
UniProt
Find proteins for P00766 (Bos taurus)
Explore P00766 
Go to UniProtKB:  P00766
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP00766
Sequence Annotations
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  • Reference Sequence
Small Molecules
Binding Affinity Annotations 
IDSourceBinding Affinity
SN1 PDBBind:  1K2I IC50: 7.80e+5 (nM) from 1 assay(s)
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.200 
  • R-Value Work: 0.180 
  • R-Value Observed: 0.190 
  • Space Group: P 42 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 69.852α = 90
b = 69.852β = 90
c = 97.38γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
CNSrefinement
CNSphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2001-12-05
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Version format compliance
  • Version 1.3: 2023-08-16
    Changes: Data collection, Database references, Derived calculations, Refinement description