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Search The CSA
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Catalytic Site Atlas

CSA LITERATURE entry for 2f61

E.C. nameglucosylceramidase
SpeciesHomo sapiens (Human)
E.C. Number (IntEnz) 3.2.1.45
CSA Homologues of 2f61There are 17 Homologs
CSA Entries With UniProtID P04062
CSA Entries With EC Number 3.2.1.45
PDBe Entry 2f61
PDBSum Entry 2f61
MACiE Entry 2f61

Literature Report

IntroductionAcid beta-glucosidase (GCase) is a 497 amino acid membrane-associated lysosomal exo-beta-glucosidase, whose defective activity leads to the Gaucher disease. GCase cleaves the beta-glucosidic linkage of its major, natural substrate, glucosylceramide, as well as synthetic beta-glucosides.
The 497 amino acid mature glycoprotein is derived from 517- or 536- amino acid precursors containing leader sequences that are removed during transit through the endoplasmic reticulum membrane. Cotranslational glycosylation occurs at four out of the five N-glycosylation sites. This glycosylation is essential for the development of the catalytically active enzyme.
The catalytic cycle of GCase is dependent on the conformational changes during the transition state. Binding of effectors to specific sites of the enzyme induce the neccessary changes required to active the enzyme.
MechansimThe catalytic cycle proceeds through a two-step reaction mechanism. Glycosylation of the active site by the substrate is followed by deglycosylation with release of beta-glucose.
1. The substrate O-glycosidic bond is protonated by Glu 235. 2. Nucleophilic Glu 340 attacks the protonated glycosidic substrate bond. 3. Glucose becomes covalently bonded and the leaving group is removed. 4. Deprotonation of water by Glu 235. 5. The activated hydroxyl ion nucleophile attacks the enzyme-substrate complex, releasing beta-glucose.
Reaction

Catalytic Sites for 2f61

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
CysA342381macie:sideChainCys 342 is located near to the active site nucleophile, Glu 340, and has significant conformational and local effects. This ensures that other residues are positioned appropriately for catalytic activity
GluA340379macie:sideChainGlu 340 attacks the substrate O-glycosidic bond, which is susceptible to nucleopphilic attack due to protonation from an acid/base reaction with Glu 235.
GluA235274macie:sideChainGlu 235 protonates the substrate O-glycosidic bond, activating it towards nucleophilic attack by Gluy 340. Deprotonation of a water molecule by an acid/base reaction liberates the hydroxyl ion, which is then able to attack the enzyme-glucose complex

Annotated By Reference To The Literature - Site 2 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
CysB342381macie:sideChainCys 342 is located near to the active site nucleophile, Glu 340, and has significant conformational and local effects. This ensures that other residues are positioned appropriately for catalytic activity
GluB340379macie:sideChainGlu 340 attacks the substrate O-glycosidic bond, which is susceptible to nucleopphilic attack due to protonation from an acid/base reaction with Glu 235.
GluB235274macie:sideChainGlu 235 protonates the substrate O-glycosidic bond, activating it towards nucleophilic attack by Gluy 340. Deprotonation of a water molecule by an acid/base reaction liberates the hydroxyl ion, which is then able to attack the enzyme-glucose complex

Literature References

Notes:Further residues are thought to have indirectly catalytic roles. Arg 120 and Asn 370 are believed to have indirect roles by maintaining an active conformation and by altering active site access. Cysteines involved in disulphide formation are essential to formation and/or preservation of an active enzyme.
Fabbro D
Human acid beta-glucosidase. Use of inhibitory and activating monoclonal antibodies to investigate the enzyme's catalytic mechanism and saposin A and C binding sites.
J Biol Chem 1991 266 15021-15027
PubMed: 1714449
Liou B
Analyses of variant acid beta-glucosidases: effects of Gaucher disease mutations.
J Biol Chem 2006 281 4242-4253
PubMed: 16293621
Grace ME
Analysis of human acid beta-glucosidase by site-directed mutagenesis and heterologous expression.
J Biol Chem 1994 269 2283-2291
PubMed: 8294487
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