Crystal structure of a Kunitz type trypsin inhibitor from Cicer arietinumL

Experimental Data Snapshot

  • Resolution: 2.80 Å
  • R-Value Free: 0.221 
  • R-Value Work: 0.196 
  • R-Value Observed: 0.197 

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Structural insights into the unique inhibitory mechanism of Kunitz type trypsin inhibitor from Cicer arietinum L.

Bendre, A.D.Suresh, C.G.Shanmugam, D.Ramasamy, S.

(2019) J Biomol Struct Dyn 37: 2669-2677

  • DOI: https://doi.org/10.1080/07391102.2018.1494633
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Kunitz-type trypsin inhibitors bind to the active pocket of trypsin causing its inhibition. Plant Kunitz-type inhibitors are thought to be important in defense, especially against insect pests. From sequence analysis of various Kunitz-type inhibitors from plants, we identified CaTI2 from chickpea as a unique variant lacking the functionally important arginine residue corresponding to the soybean trypsin inhibitor (STI) and having a distinct and unique inhibitory loop organization. To further explore the implications of these sequence variations, we obtained the crystal structure of recombinant CaTI2 at 2.8Å resolution. It is evident from the structure that the variations in the inhibitory loop facilitates non-substrate like binding of CaTI2 to trypsin, while the canonical inhibitor STI binds to trypsin in substrate like manner. Our results establish the unique mechanism of trypsin inhibition by CaTI2, which warrant further research into its substrate spectrum. Abbreviations BApNA Nα-Benzoyl-L-arginine 4-nitroanilide BPT bovine pancreatic trypsin CaTI2 Cicer arietinum L trypsin inhibitor 2 DrTI Delonix regia Trypsin inhibitor EcTI Enterolobium contortisiliquum trypsin inhibitor ETI Erythrina caffra trypsin inhibitor KTI Kunitz type inhibitor STI soybean trypsin inhibitor TKI Tamarindus indica Kunitz inhibitor Communicated By Ramaswamy H. Sarma.

  • Organizational Affiliation

    a Division of Biochemical Sciences, CSIR-National Chemical Laboratory , Pune , India.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Trypsin protein inhibitor 2
A, B
223Cicer arietinumMutation(s): 0 
Gene Names: tpi2kpi1LOC101496724
Find proteins for Q9M3Z7 (Cicer arietinum)
Explore Q9M3Z7 
Go to UniProtKB:  Q9M3Z7
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ9M3Z7
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.80 Å
  • R-Value Free: 0.221 
  • R-Value Work: 0.196 
  • R-Value Observed: 0.197 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 38.73α = 90
b = 88.22β = 108.32
c = 59.34γ = 90
Software Package:
Software NamePurpose
MOSFLMdata reduction
Aimlessdata scaling

Structure Validation

View Full Validation Report

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
Counsil for Scientific and Industrial ResearchIndia--

Revision History  (Full details and data files)

  • Version 1.0: 2018-06-20
    Type: Initial release
  • Version 1.1: 2018-08-29
    Changes: Data collection, Database references
  • Version 1.2: 2018-12-12
    Changes: Data collection, Database references
  • Version 1.3: 2019-05-29
    Changes: Data collection, Database references
  • Version 1.4: 2023-11-22
    Changes: Data collection, Database references, Refinement description