1HXE

SERINE PROTEASE


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.10 Å
  • R-Value Work: 0.151 

wwPDB Validation   3D Report Full Report


This is version 1.4 of the entry. See complete history


Literature

The molecular environment of the Na+ binding site of thrombin.

Zhang, E.Tulinsky, A.

(1997) Biophys Chem 63: 185-200

  • DOI: https://doi.org/10.1016/s0301-4622(96)02227-2
  • Primary Citation of Related Structures:  
    1HXE, 1HXF

  • PubMed Abstract: 

    When Na+ binds to thrombin, a conformational change is induced that renders the enzyme kinetically faster and more specific in the activation of fibrinogen. Two Na+ binding sites have here been identified crystallographically by exchanging Na+ with Rb+. One is intermolecular, found on the surface between two symmetry-related thrombin molecules. Since it is not present in thrombin crystal structures having different crystal systems, the other Na+ site is the functionally relevant one. The second site has octahedral coordination with the carbonyl oxygen atoms of Arg221A and Lys224 and four conserved water molecules. It is located near Asp189 of the S1 specificity site in an elongated solvent channel (8 x 18 A) formed by four antiparallel beta-strands between Cys182-Cys191 and Val213-Tyr228. This channel, extending from the active site to the opposite surface of the enzyme, was first noted in the hirudin-thrombin structure and contains about 20 conserved water molecules linked together by a hydrogen bonding network that connects to the main chain of thrombin. Although the antiparallel beta-strand interactions of the functional Na+ binding site are the same in prethrombin2, the loops between the strands are very different, so that Asp189 and Arg221A are not positioned properly for either substrate or Na+ binding in prethrombin2. A water molecule with octahedral coordination has also been identified in factor Xa at the topologically equivalent Na+ site position of thrombin. Since activated protein C shows enhanced activity with monovalant cation binding, the same position is probably utilized by Na+. Since thrombin crystals could not be grown in the absence of Na+, the cation was leached from Na(+)-bound thrombin crystals by diffusion/exchange. Although both Na+ and their coordinating water molecules were removed from the Na+ binding sites, the remainder of the thrombin structure was, unexpectedly, the same. The lack of an allosteric change is most likely attributable to crystal packing effects. Thus, the structure of the slow form remains to be established crystallographically.


  • Organizational Affiliation

    Department of Chemistry, Michigan State University, East Lansing 48824, USA.


Macromolecules
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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
THROMBINA [auth L]36Homo sapiensMutation(s): 0 
EC: 3.4.21.5
UniProt & NIH Common Fund Data Resources
Find proteins for P00734 (Homo sapiens)
Explore P00734 
Go to UniProtKB:  P00734
PHAROS:  P00734
GTEx:  ENSG00000180210 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP00734
Sequence Annotations
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  • Reference Sequence
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Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
THROMBINB [auth H]259Homo sapiensMutation(s): 0 
EC: 3.4.21.5
UniProt & NIH Common Fund Data Resources
Find proteins for P00734 (Homo sapiens)
Explore P00734 
Go to UniProtKB:  P00734
PHAROS:  P00734
GTEx:  ENSG00000180210 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP00734
Sequence Annotations
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  • Reference Sequence

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Entity ID: 3
MoleculeChains Sequence LengthOrganismDetailsImage
HIRUDIN VARIANT-1C [auth I]10Hirudo medicinalisMutation(s): 0 
UniProt
Find proteins for P01050 (Hirudo medicinalis)
Explore P01050 
Go to UniProtKB:  P01050
Entity Groups  
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UniProt GroupP01050
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.10 Å
  • R-Value Work: 0.151 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 71.5α = 90
b = 72.3β = 101
c = 73.3γ = 90
Software Package:
Software NamePurpose
RAXISIIdata collection
PROFFTrefinement
R-AXISdata reduction

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1996-11-08
    Type: Initial release
  • Version 1.1: 2008-03-24
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Atomic model, Database references, Derived calculations, Non-polymer description, Structure summary, Version format compliance
  • Version 1.3: 2024-06-05
    Changes: Data collection, Database references, Derived calculations, Other
  • Version 1.4: 2024-10-09
    Changes: Structure summary