1BZX | pdb_00001bzx

THE CRYSTAL STRUCTURE OF ANIONIC SALMON TRYPSIN IN COMPLEX WITH BOVINE PANCREATIC TRYPSIN INHIBITOR

• PDB DOI: https://doi.org/10.2210/pdb1BZX/pdb

• Classification: HYDROLASE/HYDROLASE INHIBITOR
• Organism(s): Salmo salar, Bos taurus
• Mutation(s): No 


• Deposited: 1998-11-05 Released: 1998-11-11 
• Deposition Author(s): Helland, R., Leiros, I., Berglund, G.I., Willassen, N.P., Smalas, A.O.

---

Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.10 Å
• R-Value Free: 
  0.238 (Depositor) 
• R-Value Work: 
  0.206 (Depositor) 
• R-Value Observed: 
  0.206 (Depositor) 

Starting Models: experimental

Literature

The crystal structure of anionic salmon trypsin in complex with bovine pancreatic trypsin inhibitor.

Helland, R., Leiros, I., Berglund, G.I., Willassen, N.P., Smalas, A.O.

(1998) Eur J Biochem 256: 317-324

• PubMed: 9760170 
• DOI: https://doi.org/10.1046/j.1432-1327.1998.2560317.x
• Primary Citation Related Structures: 
  1BZX


• PubMed Abstract: 
  

  The complex formed between anionic salmon trypsin (ST) and bovine pancreatic trypsin inhibitor (BPTI) has been crystallised, and the X-ray structure has been solved using the molecular replacement method. The crystals are hexagonal and belong to space group P6(1)22 with lattice parameters of a = b = 83.12 A and c = 222.15 A. Data have been collected to 2.1 A and the structure has been refined to a crystallographic R-factor of 20.6%. Catalysis by salmon trypsin is distinguished by a Km value 20-fold lower than that for mammalian trypsins, and a k(cat) twice as high. The present ST-BPTI complex serves as a model for the Michaelis-Menten complex, and has been compared with corresponding bovine and rat trypsin (RT) complexes. The binding of BPTI to salmon trypsin is characterised by stronger primary interactions in the active site, and a somewhat looser secondary binding.

---

Organizational Affiliation: 
• Department of Chemistry, University of Tromsø, Norway.

Biological Assembly 1  

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Hetero 2-mer - A1B1 

Biological assembly 1 assigned by authors and generated by PISA (software)

Macromolecule Content 

• Total Structure Weight: 30.43 kDa 
• Atom Count: 2,219 
• Modeled Residue Count: 280 
• Deposited Residue Count: 280 
• Unique protein chains: 2

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
PROTEIN (TRYPSIN)	A [auth E]	222	Salmo salar	Mutation(s): 0  EC: 3.4.21.4
UniProt
Find proteins for P35031 (Salmo salar) Explore P35031  Go to UniProtKB:  P35031

Entity ID: 2
Molecule	Chains	Sequence Length	Organism	Details	Image
PROTEIN (BOVINE PANCREATIC TRYPSIN INHIBITOR)	B [auth I]	58	Bos taurus	Mutation(s): 0
UniProt
Find proteins for P00974 (Bos taurus) Explore P00974  Go to UniProtKB:  P00974

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
CA	C [auth E]	CALCIUM ION Ca BHPQYMZQTOCNFJ-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.10 Å
• R-Value Free:  0.238 (Depositor) 
• R-Value Work:  0.206 (Depositor) 
• R-Value Observed: 0.206 (Depositor) 

Space Group: P 6₁ 2 2

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 84.12	α = 90
b = 84.12	β = 90
c = 222.15	γ = 120

Software Package:

Software Name	Purpose
DENZO	data reduction
CCP4	data reduction
X-PLOR	model building
X-PLOR	refinement
CCP4	data scaling
X-PLOR	phasing

Structure Validation

Entry History 

Deposition Data

• Released Date: 1998-11-11 
Deposition Author(s): Helland, R., Leiros, I., Berglund, G.I., Willassen, N.P., Smalas, A.O.

Revision History  

• Version 1.0: 1998-11-11
  Type: Initial release
  
• Version 1.1: 2008-04-27
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Version format compliance
• Version 1.3: 2023-08-09
  Changes: Data collection, Database references, Derived calculations, Refinement description
• Version 1.4: 2024-11-20
  Changes: Structure summary