Experimental Data Snapshot

  • Resolution: 2.40 Å
  • R-Value Free: 0.175 
  • R-Value Work: 0.181 
  • R-Value Observed: 0.181 

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This is version 1.3 of the entry. See complete history


X-ray structure of an anti-fungal chitosanase from streptomyces N174.

Marcotte, E.M.Monzingo, A.F.Ernst, S.R.Brzezinski, R.Robertus, J.D.

(1996) Nat Struct Biol 3: 155-162

  • DOI: https://doi.org/10.1038/nsb0296-155
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    We report the 2.4 A X-ray crystal structure of a protein with chitosan endo-hydrolase activity isolated from Streptomyces N174. The structure was solved using phases acquired by SIRAS from a two-site methyl mercury derivative combined with solvent flattening and non-crystallographic two-fold symmetry averaging, and refined to an R-factor of 18.5%. The mostly alpha-helical fold reveals a structural core shared with several classes of lysozyme and barley endochitinase, in spite of a lack of shared sequence. Based on this structural similarity we postulate a putative active site, mechanism of action and mode of substrate recognition. It appears that Glu 22 acts as an acid and Asp 40 serves as a general base to activate a water molecule for an SN2 attack on the glycosidic bond. A series of amino-acid side chains and backbone carbonyl groups may bind the polycationic chitosan substrate in a deep electronegative binding cleft.

  • Organizational Affiliation

    Department of Chemistry and Biochemistry, University of Texas, Austin 78712, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B
238Streptomyces sp. N174Mutation(s): 0 
Gene Names: CSN
Find proteins for P33665 (Streptomyces sp. (strain N174))
Explore P33665 
Go to UniProtKB:  P33665
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP33665
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.40 Å
  • R-Value Free: 0.175 
  • R-Value Work: 0.181 
  • R-Value Observed: 0.181 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 56.3α = 90
b = 59.3β = 96.2
c = 85.4γ = 90
Software Package:
Software NamePurpose
X-PLORmodel building
SDMSdata reduction
SDMSdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1996-07-11
    Type: Initial release
  • Version 1.1: 2008-03-24
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Source and taxonomy, Version format compliance
  • Version 1.3: 2024-02-07
    Changes: Data collection, Database references, Other