|Protein name||cellulaseendo-1,4-beta-D-glucanasebeta-1,4-glucanasebeta-1,4-endoglucan hydrolasecelluase Acellulosin APendoglucanase Dalkali cellulasecellulase A 3celludextrinase9.5 cellulaseavicelasepancellase SS1,4-(1,31,4)-beta-D-glucan 4-glucanohydrolase|
|Synonyms||Endoglucanase AEC 18.104.22.168|
|CAZy||GH12 (Glycoside Hydrolase Family)|
|MAP00500||Starch and sucrose metabolism|
|Compound table: links to PDB-related databases & PoSSuM|
|Compound||Cellulose||Lichenin||beta-D-Glucan||H2O||Cellulose||beta-D-Glucan||Transition-state for glycosylated enzyme||Glycosylated enzyme intermediate|
| || || || || || || || || || || || || || || || |
|1ks4A||Unbound||Unbound||Unbound|| ||Unbound||Unbound|| || |
|1ks5A||Unbound||Unbound||Unbound|| ||Unbound||Unbound|| || |
|References for Catalytic Mechanism|
|References||Sections||No. of steps in catalysis|
|Comments||X-RAY CRYSTALLOGRAPHY (2.1 ANGSTROMS) OF 17-239.|
|Journal||Acta Crystallogr D Biol Crystallogr|
|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.|
|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.
According to the literature , 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.
(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.