Structure of the wild-type cellobiohydrolase Cel6A from Humicolas insolens in complex with a fluorescent substrate

Experimental Data Snapshot

  • Resolution: 1.75 Å
  • R-Value Free: 0.168 
  • R-Value Work: 0.133 
  • R-Value Observed: 0.135 

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Structural Basis for Ligand Binding and Processivity in Cellobiohydrolase Cel6A from Humicola Insolens

Varrot, A.Frandsen, T.P.Von Ossowski, I.Boyer, V.Driguez, H.Schulein, M.Davies, G.J.

(2003) Structure 11: 855

  • DOI: https://doi.org/10.1016/s0969-2126(03)00124-2
  • Primary Citation of Related Structures:  
    1OC5, 1OC6, 1OC7, 1OCB, 1OCJ

  • PubMed Abstract: 

    The enzymatic digestion of cellulose entails intimate involvement of cellobiohydrolases, whose characteristic active-center tunnel contributes to a processive degradation of the polysaccharide. The cellobiohydrolase Cel6A displays an active site within a tunnel formed by two extended loops, which are known to open and close in response to ligand binding. Here we present five structures of wild-type and mutant forms of Cel6A from Humicola insolens in complex with nonhydrolyzable thio-oligosaccharides, at resolutions from 1.7-1.1 A, dissecting the structural accommodation of a processing substrate chain through the active center during hydrolysis. Movement of ligand is facilitated by extensive solvent-mediated interactions and through flexibility in the hydrophobic surfaces provided by a sheath of tryptophan residues.

  • Organizational Affiliation

    Department of Chemistry, University of York, Heslington, Y010 5YW, York, United Kingdom.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B
362Humicola insolensMutation(s): 0 
Find proteins for Q9C1S9 (Humicola insolens)
Explore Q9C1S9 
Go to UniProtKB:  Q9C1S9
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ9C1S9
Sequence Annotations
  • Reference Sequence


Entity ID: 2
MoleculeChains Length2D Diagram Glycosylation3D Interactions
4-amino-4-deoxy-alpha-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-methyl 4-thio-beta-D-glucopyranoside
C, E
Glycosylation Resources
GlyTouCan:  G84956EQ
GlyCosmos:  G84956EQ
Entity ID: 3
MoleculeChains Length2D Diagram Glycosylation3D Interactions
beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-methyl 4-thio-beta-D-glucopyranoside
D, F
Glycosylation Resources
GlyTouCan:  G22306SE
GlyCosmos:  G22306SE
Experimental Data & Validation

Experimental Data

  • Resolution: 1.75 Å
  • R-Value Free: 0.168 
  • R-Value Work: 0.133 
  • R-Value Observed: 0.135 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 49.763α = 90
b = 155.681β = 118.42
c = 51.218γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2003-07-10
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Advisory, Version format compliance
  • Version 2.0: 2020-06-24
    Changes: Atomic model, Data collection, Derived calculations, Other
  • Version 3.0: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Advisory, Atomic model, Data collection, Derived calculations, Structure summary
  • Version 3.1: 2023-12-13
    Changes: Data collection, Database references, Refinement description, Structure summary