1QLQ

Bovine Pancreatic Trypsin Inhibitor (BPTI) Mutant with Altered Binding Loop Sequence


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.42 Å
  • R-Value Free: 0.161 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

High Resolution Structure of Bovine Pancreatic Trypsin Inhibitor with Altered Binding Loop Sequence

Czapinska, H.Otlewski, J.Krzywda, S.Sheldrick, G.M.Jaskolski, M.

(1999) J.Mol.Biol. 295: 1237

  • DOI: 10.1006/jmbi.1999.3445

  • PubMed Abstract: 
  • A mutant of bovine pancreatic trypsin inhibitor (BPTI) has been constructed and expressed in Escherichia coli in order to probe the kinetic and structural consequences of truncating the binding loop residues to alanine. In addition to two such mutati ...

    A mutant of bovine pancreatic trypsin inhibitor (BPTI) has been constructed and expressed in Escherichia coli in order to probe the kinetic and structural consequences of truncating the binding loop residues to alanine. In addition to two such mutations (Thr11Ala and Pro13Ala), it has a conservative Lys15Arg substitution at position P(1) and an unrelated Met52Leu change. In spite of the binding loop modification, the affinity for trypsin is only 30 times lower than that of the wild-type protein. At pH 7.5 the protein can be crystallized on the time-scale of hours, yielding very stable crystals of a new (tetragonal) form of BPTI. Conventional source X-ray data collected to 1.4 A at room temperature allowed anisotropic structure refinement characterized by R=0.1048. The structure reveals all 58 residues, including the complete C terminus, which is in a salt-bridge contact with the N terminus. The Cys14-Cys38 disulfide bridge is observed in two distinct chiralities. This bridge, together with an internal water molecule, contributes to the stabilization of the binding loop. The Ala mutations have only an insignificant and localized effect on the binding loop, which retains its wild-type conformation (maximum deviation of loop C(alpha) atoms of 0.7 A at Ala13). Four (instead of the typical three) additional water molecules are buried in an internal cleft and connected to the surface via a sulfate anion. Three more SO(4)(2-) anions are seen in the electron density, one of them located on a 2-fold axis. It participates in the formation of a dimeric structure between symmetry-related BPTI molecules, in which electrostatic and hydrogen bonding interactions resulting from the mutated Lys15Arg substitution are of central importance. This dimeric interaction involves direct recognition loop-recognition loop contacts, part of which are hydrophobic interactions of the patches created by the alanine mutations. Another 2-fold symmetric interaction between the BPTI molecules involves the formation of an antiparallel intermolecular beta-sheet that, together with the adjacent intramolecular beta-hairpin loops, creates a four-stranded structure.


    Related Citations: 
    • Structure of Bovine Pancreatic Trypsin Inhibitor . Results of Joint Neutron and X-Ray Refinement of Crystal Form II
      Wlodawer, A.,Walter, J.,Huber, R.,Sjolin, L.
      (1984) J.Mol.Biol. 180: 301
    • Determination of a High Quality Nuclear Magnetic Resonance Solution Structure of the Bovine Pancreatic Trypsin Inhibitor and Comparison with Three Crystal Structures
      Berndt, K.,Guentert, P.,Orbons, L.P.,Wuethrich, K.
      (1992) J.Mol.Biol. 227: 757
    • Crystallographic Refinement of the Structure of Bovine Pancreatic Trypsin Inhibitor at 1.5 A Resolution
      Deisenhofer, J.,Steigemann, W.
      (1975) Acta Crystallogr.,Sect.B 31: 238
    • Structure of Bovine Pancreatic Trypsin Inhibitor at 125 K: Definition of Carboxyl-Terminal Residues Gly57 and Ala58
      Parkin, S.,Rupp, B.,Hope, H.
      (1996) Acta Crystallogr.,Sect.D 52: 19


    Organizational Affiliation

    Department of Protein Engineering, Institute of Biochemistry and Molecular Biology, University of Wroclaw, Tamka 2, Wroclaw, 50-137, Poland.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
PANCREATIC TRYPSIN INHIBITOR
A
58Bos taurusMutation(s): 4 
Find proteins for P00974 (Bos taurus)
Go to UniProtKB:  P00974
Small Molecules
Ligands 1 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
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.42 Å
  • R-Value Free: 0.161 
  • Space Group: P 43 21 2
Unit Cell:
Length (Å)Angle (°)
a = 52.710α = 90.00
b = 52.710β = 90.00
c = 43.410γ = 90.00
Software Package:
Software NamePurpose
SHELXL-97phasing
SCALEPACKdata scaling
DENZOdata reduction
SHELXL-97refinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1999-10-05
    Type: Initial release
  • Version 1.1: 2011-05-08
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2018-06-06
    Type: Data collection, Structure summary