1WBC

CRYSTALLIZATION AND PRELIMINARY X-RAY STUDIES OF PSOPHOCARPIN B1, A CHYMOTRYPSIN INHIBITOR FROM WINGED BEAN SEEDS


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.95 Å
  • R-Value Work: 0.191 
  • R-Value Observed: 0.191 

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This is version 1.3 of the entry. See complete history


Literature

Structure of a Kunitz-type chymotrypsin from winged bean seeds at 2.95 A resolution.

Dattagupta, J.K.Podder, A.Chakrabarti, C.Sen, U.Dutta, S.K.Singh, M.

(1996) Acta Crystallogr D Biol Crystallogr 52: 521-528

  • DOI: https://doi.org/10.1107/S0907444996000224
  • Primary Citation of Related Structures:  
    1WBC

  • PubMed Abstract: 

    Thc crystal structure of an alpha-chymotrypsin inhibitor (P6(1)22; a = 61.4, c = 210.9 A) isolated from winged bean (Psophocarpus. tetragonolobus) seeds has been determined at 2.95 A resolution by the molecular-replacement method using the 2.6 A coordinates of Erythrina trypsin inhibitor (ETI) as the starting model (57% sequence homology). This protease inhibitor, WCI, belongs to the Kunitz (STI) family and is a single polypeptide chain with 183 amino-acid residues having a molecular weight of 20 244 Da. Structure refinement with RESTRAIN and X-PLOR has led to a crystallographic R factor of 19.1% for 3469 observed reflections (I > 2sigma) in the resolution range 8-2.95 A. A total of 56 water molecules have been incorporated in the refined model containing 181 amino-acid residues. In the refined structure the deviations of bond lengths and bond angles from ideal values are 0.015 A and 2.2 degrees, respectively. The inhibitor molecule is spherical and consists of 12 antiparallel beta-strands with connecting loops arranged in a characteristic folding (a six-stranded beta-barrel and a six-stranded lid on one hollow end of the barrel) common to other homologous serine protease inhibitors in the Kunitz (STI) family as well as to some non-homologous proteins like interleukin-lalpha and interleukin-lbeta. In the structure the conformation of the protruding reactive-site loop is stabilized through hydrogen bonds mainly formed by the side chain of Asnl4, which intrudes inside the cavity of the reactive-site loop, with the side-chain and main-chain atoms of some residues in the loop region. A pseudo threefold axis exists parallel to the barrel axis of the structure. Each of the three subdomains comprises of four beta-strands with connecting loops.


  • Organizational Affiliation

    Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Bidhan Nagar, Calcutta, India.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
CHYMOTRYPSIN INHIBITOR (WCI)183Psophocarpus tetragonolobusMutation(s): 0 
UniProt
Find proteins for P10822 (Psophocarpus tetragonolobus)
Explore P10822 
Go to UniProtKB:  P10822
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP10822
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.95 Å
  • R-Value Work: 0.191 
  • R-Value Observed: 0.191 
  • Space Group: P 61 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 61.4α = 90
b = 61.4β = 90
c = 210.9γ = 120
Software Package:
Software NamePurpose
X-PLORmodel building
X-PLORrefinement
X-PLORphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1996-04-03
    Type: Initial release
  • Version 1.1: 2008-03-04
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2017-11-29
    Changes: Advisory, Derived calculations, Other