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Catalytic Site Atlas Search Results
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Catalytic Site Atlas

CSA LITERATURE entry for 2bsx

E.C. namepurine-nucleoside phosphorylase
SpeciesPlasmodium falciparum ()
E.C. Number (IntEnz) 2.4.2.1
CSA Homologues of 2bsx
CSA Entries With UniProtID
CSA Entries With EC Number 2.4.2.1
PDBe Entry 2bsx
PDBSum Entry 2bsx
MACiE Entry 2bsx

Literature Report

IntroductionPurine metabolism in the parasite Plasmodium has been identified as a promising target for anitmalerial therapies. Purine nucleoside phosphorylase (PNP) is part of a salvage pathway for the biosynthesis of purines, which are essential to parasite survival.
MechansimIn the case of ribonucleosides, bond breaking occurs well ahead of bond formation in the phosphorolytic direction, leading to the proposal of an oxocarbenium intermediate. The leaving group (the purine base) is stabilized by a hydrogen bond from protonated Asp204 to purine N7 as it moves towards this residue during bond cleavage. As the glycosidic bond begins to cleave, the resulting oxocarbenium ion is probably stabilized by the negatively charged phosphate group, since no amino acid side chain is available for this purpose. The reaction is completed by bond formation when the phosphate ion captures the oxocarbenium intermediate.
Reaction

Catalytic Sites for 2bsx

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
AspA206206macie:sideChainProvides a proton to N7 of the purine as the glycosidic bond cleaves.

Literature References

Notes:
Schnick C
Structures of Plasmodium falciparum purine nucleoside phosphorylase complexed with sulfate and its natural substrate inosine.
Acta Crystallogr D Biol Crystallogr 2005 61 1245-1254
PubMed: 16131758
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