1BVW

CELLOBIOHYDROLASE II (CEL6A) FROM HUMICOLA INSOLENS


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.92 Å
  • R-Value Free: 0.210 
  • R-Value Work: 0.142 

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This is version 1.3 of the entry. See complete history


Literature

Crystal structure of the catalytic core domain of the family 6 cellobiohydrolase II, Cel6A, from Humicola insolens, at 1.92 A resolution.

Varrot, A.Hastrup, S.Schulein, M.Davies, G.J.

(1999) Biochem J 337: 297-304

  • Primary Citation of Related Structures:  
    1BVW

  • PubMed Abstract: 
  • The three-dimensional structure of the catalytic core of the family 6 cellobiohydrolase II, Cel6A (CBH II), from Humicola insolens has been determined by X-ray crystallography at a resolution of 1.92 A. The structure was solved by molecular replacement using the homologous Trichoderma reesei CBH II as a search model ...

    The three-dimensional structure of the catalytic core of the family 6 cellobiohydrolase II, Cel6A (CBH II), from Humicola insolens has been determined by X-ray crystallography at a resolution of 1.92 A. The structure was solved by molecular replacement using the homologous Trichoderma reesei CBH II as a search model. The H. insolens enzyme displays a high degree of structural similarity with its T. reesei equivalent. The structure features both O- (alpha-linked mannose) and N-linked glycosylation and a hexa-co-ordinate Mg2+ ion. The active-site residues are located within the enclosed tunnel that is typical for cellobiohydrolase enzymes and which may permit a processive hydrolysis of the cellulose substrate. The close structural similarity between the two enzymes implies that kinetics and chain-end specificity experiments performed on the H. insolens enzyme are likely to be applicable to the homologous T. reesei enzyme. These cast doubt on the description of cellobiohydrolases as exo-enzymes since they demonstrated that Cel6A (CBH II) shows no requirement for non-reducing chain-ends, as had been presumed. There is no crystallographic evidence in the present structure to support a mechanism involving loop opening, yet preliminary modelling experiments suggest that the active-site tunnel of Cel6A (CBH II) is too narrow to permit entry of a fluorescenyl-derivatized substrate, known to be a viable substrate for this enzyme.


    Organizational Affiliation

    Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York Y01 5DD, U.K.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
PROTEIN (CELLOBIOHYDROLASE II)A360Humicola insolensMutation(s): 0 
Gene Names: cel6Aavi2
EC: 3.2.1.91
UniProt
Find proteins for Q9C1S9 (Humicola insolens)
Explore Q9C1S9 
Go to UniProtKB:  Q9C1S9
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 4 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NAG (Subject of Investigation/LOI)
Query on NAG

Download Ideal Coordinates CCD File 
D [auth A]2-acetamido-2-deoxy-beta-D-glucopyranose
C8 H15 N O6
OVRNDRQMDRJTHS-FMDGEEDCSA-N
 Ligand Interaction
MAN (Subject of Investigation/LOI)
Query on MAN

Download Ideal Coordinates CCD File 
B [auth A], C [auth A]alpha-D-mannopyranose
C6 H12 O6
WQZGKKKJIJFFOK-PQMKYFCFSA-N
 Ligand Interaction
GOL
Query on GOL

Download Ideal Coordinates CCD File 
F [auth A]GLYCEROL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
 Ligand Interaction
MG
Query on MG

Download Ideal Coordinates CCD File 
E [auth A]MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.92 Å
  • R-Value Free: 0.210 
  • R-Value Work: 0.142 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 47.51α = 90
b = 68.1β = 110.93
c = 53.71γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
AMoREphasing
REFMACrefinement

Structure Validation

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Ligand Structure Quality Assessment  



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1999-09-18
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Non-polymer description, Version format compliance
  • Version 1.3: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Data collection, Derived calculations, Structure summary