1BRB image
Entry Detail
PDB ID:
1BRB
Title:
CRYSTAL STRUCTURES OF RAT ANIONIC TRYPSIN COMPLEXED WITH THE PROTEIN INHIBITORS APPI AND BPTI
Biological Source:
Source Organism:
PDB Version:
Deposition Date:
1992-12-17
Release Date:
1994-07-31
Method Details:
Experimental Method:
Resolution:
2.10 Å
R-Value Work:
0.19
R-Value Observed:
0.19
Space Group:
P 32 2 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:TRYPSIN
Chain IDs:A (auth: E)
Chain Length:223
Number of Molecules:1
Biological Source:Rattus norvegicus
Primary Citation
Crystal structures of rat anionic trypsin complexed with the protein inhibitors APPI and BPTI.
J.Mol.Biol. 230 919 933 (1993)
PMID: 7683059 DOI: 10.1006/jmbi.1993.1210

Abstact

The crystal structure of rat anionic trypsin D189G/G226D has been determined in complexes with each of the protein inhibitors APPI (amyloid beta-protein precursor inhibitor domain) and BPTI (bovine pancreatic trypsin inhibitor) at resolutions of 2.5 A and 2.1 A, respectively. Comparisons with the structure of the bovine trypsin-BPTI complex show that the enzyme-inhibitor interactions in rat trypsin are dominated to a much greater degree by attractive and repulsive electrostatic forces. Decreased structural complementarity in the flanking regions of the interface formed with BPTI is reflected in significantly weaker inhibition relative to bovine trypsin. The primary active site loop of BPTI adopts slightly different conformations when bound to rat and cow trypsins, reflecting a broader entrance to the binding pocket in the former. Tight complementarity of each loop conformer to the respective active sites then gives rise to significantly different overall orientations of the inhibitor when bound to the two enzymes. The crystal structures of trypsin bound to these protein inhibitors are excellent models of the Michaelis complexes, which permit visualization of substrate interactions both N and C-terminal to the cleaved bond, while maintaining identical reaction chemistry. They will be uniquely useful to the structure-function analysis of variant rat trypsin enzymes.

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Primary Citation of related structures