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Search The CSA
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Catalytic Site Atlas

CSA LITERATURE entry for 1lio

E.C. nameadenosine kinase
SpeciesToxoplasma gondii (Protozoan)
E.C. Number (IntEnz) 2.7.1.20
CSA Homologues of 1lioThere are 38 Homologs
CSA Entries With UniProtID Q9TVW2
CSA Entries With EC Number 2.7.1.20
PDBe Entry 1lio
PDBSum Entry 1lio
MACiE Entry M0209

Literature Report

IntroductionToxoplasma gondii Adenosine kinase is able to catalyse the formation of AMP and ATP using ATP to phosphorylate Adenosine. It thus belongs to the family of ribokinases that have significant sequence homology. The importance of the enzyme to the organism is paramount- it is necessary for purine biosynthesis. Therefore it represents an attractive target for drugs which attack this highly dangerous parasite.
MechansimThe reaction proceeds through a single step Sn2-like mechanism with nucleophilic attack on the gamma phosphate of ATP by the 3C OH of the ribose sugar, facilitated by deprotonation of the OH by Asp 318. The protonation of the ADP leaving group is achieved by a catalytic water molecule, and the pentavalent phosphate intermediate is stabilised by Arg 136 and a Mg2+ ion.
Reaction

Catalytic Sites for 1lio

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
ArgA136136macie:sideChainStabilises the pentavalent phosphate transition state through its positive charge interacting favourably with the negative charge developed. This allows nucleophilic attack from the adenosine on the gamma phosphate.
AspA318318macie:sideChainActivates adenosine towards nucleophilic attack on the gamma phosphate of ATP.

Literature References

Notes:
Schumacher MA
Crystal structures of Toxoplasma gondii adenosine kinase reveal a novel catalytic mechanism and prodrug binding.
J Mol Biol 2000 298 875-893
PubMed: 10801355
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