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Catalytic Site Atlas

CSA LITERATURE entry for 1euu

E.C. nameexo-alpha-sialidase
SpeciesMicromonospora viridifaciens ()
E.C. Number (IntEnz) 3.2.1.18
CSA Homologues of 1euuThere are 23 Homologs
CSA Entries With UniProtID Q02834
CSA Entries With EC Number 3.2.1.18
PDBe Entry 1euu
PDBSum Entry 1euu
MACiE Entry 1euu

Literature Report

IntroductionExo sialidases (neuraminidases) catalyse the removal of terminal sialic acid residues in oligosaccharides, glycoproteins, glycolipids and synthetic substrates to release free sialic acid. They have roles in pathogenesis, bacterial nutrition and cellular interactions. Hydrolysis of the sialyl ketal linkages occurs with retention of anomeric configuration, consistent with this family of enzymes operating via a standard double-displacement mechanism.
MechansimThe three catalytic residues are Tyr 370, Glu 260 and Asp 92. Tyr 370 acts as a nucleophile to attack the C1 carbon of sialic acid in an SN2 mechanism, with concerted displacement of the glycoconjagate to which the sialic acid is attached. The departing oxygen atom of the sialyl ketal linkage is protonated by Asp 92. Glu 260 functions to deprotonate Tyr 370 as it attacks the sialic acid. In the second step, Asp 92 deprotates a water molecule that attacks C1 of the intermediate to displace Tyr 370 and generate sialic acid.
Reaction

Catalytic Sites for 1euu

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
AspA9292macie:sideChainProtonates the departing oxygen of the sialyl ketal linkage. Deprotonates the water molecule that attacks the tyrosine-linked intermediate.
TyrA370370macie:sideChainAttacks the C1 carbon of sialic acid to displace the glycoconjugate in an SN2 mechanism.
GluA260260macie:sideChainDeprotonates Tyr 370 which acts as a nucleophile to attack C1 of the sialic acid.

Literature References

Notes:
Watson JN
Mutagenesis of the conserved active-site tyrosine changes a retaining sialidase into an inverting sialidase.
Biochemistry 2003 42 12682-12690
PubMed: 14580216
Gaskell A
The three domains of a bacterial sialidase: a beta-propeller, an immunoglobulin module and a galactose-binding jelly-roll.
Structure 1995 3 1197-1205
PubMed: 8591030
Watts AG
Trypanosoma cruzi trans-sialidase operates through a covalent sialyl-enzyme intermediate: tyrosine is the catalytic nucleophile.
J Am Chem Soc 2003 125 7532-7533
PubMed: 12812490
Amaya MF
Structural insights into the catalytic mechanism of Trypanosoma cruzi trans-sialidase.
Structure 2004 12 775-784
PubMed: 15130470
Watson JN
Contribution of the active site aspartic acid to catalysis in the bacterial neuraminidase from Micromonospora viridifaciens.
FEBS Lett 2004 577 265-269
PubMed: 15527797
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