DB code: S00533

RLCP classification 1.30.36211.1000 : Hydrolysis
CATH domain 2.60.120.180 : Jelly Rolls Catalytic domain
E.C. 3.2.1.4
CSA
M-CSA
MACiE

CATH domain Related DB codes (homologues)
2.60.120.180 : Jelly Rolls S00150 S00151 D00504 D00538

Uniprot Enzyme Name
UniprotKB Protein name Synonyms CAZy Pfam
O74705
Endoglucanase A
EC 3.2.1.4
GH12 (Glycoside Hydrolase Family 12)
PF01670 (Glyco_hydro_12)
[Graphical View]

KEGG enzyme name
cellulase
endo-1,4-beta-D-glucanase
beta-1,4-glucanase
beta-1,4-endoglucan hydrolase
celluase A
cellulosin AP
endoglucanase D
alkali cellulase
cellulase A 3
celludextrinase
9.5 cellulase
avicelase
pancellase SS
1,4-(1,3
1,4)-beta-D-glucan 4-glucanohydrolase

UniprotKB: Accession Number Entry name Activity Subunit Subcellular location Cofactor
O74705 O74705_ASPNG

KEGG Pathways
Map code Pathways E.C.
MAP00500 Starch and sucrose metabolism

Compound table
Substrates Products Intermediates
KEGG-id C00760 C00478 C00551 C00001 C00760 C00551
E.C.
Compound Cellulose Lichenin beta-D-Glucan H2O Cellulose beta-D-Glucan Transition-state for glycosylated enzyme Glycosylated enzyme intermediate
Type polysaccharide carbohydrate polysaccharide H2O polysaccharide polysaccharide
ChEBI 15377
PubChem 439241
46173706
22247451
962
46173706
1ks4A Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Unbound Unbound Unbound Unbound Unbound
1ks5A Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain Unbound Unbound Unbound Unbound Unbound

Reference for Active-site residues
resource references E.C.
PDB;1h8v, literature [2], [4]

Active-site residues
PDB Catalytic residues Cofactor-binding residues Modified residues Main-chain involved in catalysis Comment
1ks4A Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain ASP 95;ASP 99;GLU 116;GLU 204
1ks5A Pdbj logo s Rasmollogo id Rasmollogo chain Mmcif id Mmcif chain ASP 95;ASP 99;GLU 116;GLU 204

References for Catalytic Mechanism
References Sections No. of steps in catalysis
[1]
p.663-664

References
[1]
Resource
Comments X-RAY CRYSTALLOGRAPHY (2.1 ANGSTROMS) OF 17-239.
Medline ID
PubMed ID 11914491
Journal Acta Crystallogr D Biol Crystallogr
Year 2002
Volume 58
Pages 660-7
Authors Khademi S, Zhang D, Swanson SM, Wartenberg A, Witte K, Meyer EF
Title Determination of the structure of an endoglucanase from Aspergillus niger and its mode of inhibition by palladium chloride.
Related PDB 1ks4 1ks5
Related UniProtKB O74705

Comments
According to the literature [1], the catalytic reaction proceeds as follows:
(1) Asp95 may modulate the activity of Glu204 as a acid-base.
(2) Glu204 acts as a general acid to protonate the leaving oxygen atom, leading to a oxocarbenium-like transtion state from cellulose substrate.
(3) pKa of Glu116, which acts as a nucleophile, is modulated by Asp99.
This family belongs to glycosidase family-12, which has a retaining mechanism.
The catalytic domain of this enzyme is homologous to those of another cellulase (S00150 in EzCatDB) and beta-1,4-Glucanase (D00504 in EzCatDB), whose catalytic mechanisms must be similar to that of this enzyme.
(4) Glu116 makes a nucleophilic attack on C1 atom of the transition state, forming a glycosyl-enzyme intermediate.
(5) Glu204 acts as a general base to activate a water molecule.
(6) The activated water makes a nucleophilic attack on the C1 atom of the intermediate. This reaction proceeds through an oxocarbenium-like transition state to complete the hydrolysis.

Created Updated
2004-05-17 2009-02-26