1TLD

CRYSTAL STRUCTURE OF BOVINE BETA-TRYPSIN AT 1.5 ANGSTROMS RESOLUTION IN A CRYSTAL FORM WITH LOW MOLECULAR PACKING DENSITY. ACTIVE SITE GEOMETRY, ION PAIRS AND SOLVENT STRUCTURE


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.5 Å
  • R-Value Work: 0.167 

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This is version 1.3 of the entry. See complete history

Literature

Crystal structure of bovine beta-trypsin at 1.5 A resolution in a crystal form with low molecular packing density. Active site geometry, ion pairs and solvent structure.

Bartunik, H.D.Summers, L.J.Bartsch, H.H.

(1989) J.Mol.Biol. 210: 813-828


  • PubMed Abstract: 
  • The crystal structure of bovine pancreatic beta-trypsin (BPT) has been determined from a novel orthorhombic crystal form which contains substantially more solvent (filling 57% of the volume of the unit cell) than previously determined orthorhombic (4 ...

    The crystal structure of bovine pancreatic beta-trypsin (BPT) has been determined from a novel orthorhombic crystal form which contains substantially more solvent (filling 57% of the volume of the unit cell) than previously determined orthorhombic (44%) and trigonal (37%) BPT structures. The native and benzamidine-inhibited crystal structures of BPT in ammonium sulphate at pH 5.3 have been determined for the new form by molecular replacement techniques. The structures have been refined at 1.5 A resolution with final R-values of 16.7% and 16.9%, respectively. Comparison with the previously refined old orthorhombic forms shows that the overall conformation of the protein backbone is highly conserved. A great number of previously undefined side-chains have been located in density. At the C terminus an extra ion pair involving lysines 87 and 107 has been revealed. A far more detailed picture of the ordered solvent structure has been derived. Thirty water clusters have been identified. A large water network extends from the calcium binding site to the activation area and the autolysis loop. There is evidence for a water channel reaching from the depth of the specificity pocket to the nearby protein surface which might be involved in the displacement of water molecules upon substrate binding. A sulphate anion which forms hydrogen bonds to the active site residues His57, Ser195 and Gly193 was for the first time positioned in clearly defined electron density. Interaction with the sulphate ion may explain the increase in the pKa value of His57 at high sulphate concentrations which was observed by nuclear magnetic resonance studies of a bacterial serine protease both in crystalline form and in solution. Thus, a His-Ser hydrogen bond will not exist in solvents containing sulphate at low pH (up to at least 6.8) where the imidazole of His57 is protonated. The new crystal form is of considerable interest for substrate binding studies. Wide solvent channels should allow diffusion of large substrates (comparable in size to, e.g. pancreatic trypsin inhibitor) into the enzyme crystal. The active site is accessible; intermolecular contact areas are further remote from the active site than in the old orthorhombic form.


    Related Citations: 
    • On the Disordered Activation Domain in Trypsinogen. Chemical Labelling and Low Temperature Crystallography
      Walter, J.,Steigemann, W.,Singh, T.P.,Bartunik, H.D.,Bode, W.,Huber, R.
      (1982) Acta Crystallogr.,Sect.B 38: 1462
    • The Geometry of the Reactive Site and of the Peptide Groups in Trypsin, Trypsinogen and its Complexes with Inhibitors
      Marquart, M.,Walter, J.,Deisenhofer, J.,Bode, W.,Huber, R.
      (1983) Acta Crystallogr.,Sect.B 39: 480


    Organizational Affiliation

    Max-Planck-Society, Research Unit for Structural Molecular Biology, Hamburg, West Germany.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
BETA-TRYPSIN
A
223Bos taurusEC: 3.4.21.4
Find proteins for P00760 (Bos taurus)
Go to UniProtKB:  P00760
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SO4
Query on SO4

Download SDF File 
Download CCD File 
A
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
CA
Query on CA

Download SDF File 
Download CCD File 
A
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.5 Å
  • R-Value Work: 0.167 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 63.700α = 90.00
b = 63.500β = 90.00
c = 68.900γ = 90.00
Software Package:
Software NamePurpose
FILMEdata reduction
PROTEINdata scaling
PROTEINmodel building
EREFrefinement
PROTEINphasing

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1990-01-15
    Type: Initial release
  • Version 1.1: 2008-03-24
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2012-06-06
    Type: Data collection, Database references