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Catalytic Site Atlas Version 2.2.12
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CSA entry for 1lij
Original Entry
Title:
Transferase
Compound:
Adenosine kinase
Mutant:
No
UniProt/Swiss-Prot:
Q9TVW2-ADK_TOXGO
EC Class:
2.7.1.20
Other CSA Entries:
Overview of all sites for 1lij
Homologues of 1lij
Entries for UniProt/Swiss-Prot: Q9TVW2
Entries for EC: 2.7.1.20
Other Databases:
PDB entry: 1lij
PDBsum entry: 1lij
UniProt/Swiss-Prot: Q9TVW2
IntEnz entry: 2.7.1.20
Literature Report:
Introduction:
Toxoplasma gondii adenosine kinase catalyses the transfer of phosphoryl group from ATP to adenosine to yield AMP and ADP. It belongs to the family of carbohydrate kinases.

Like all parasitic protozoans, T.gondii cannot synthesise purine bases de novo, so enzymes of the T.gondii purine salvage pathway are required for parasite survival. Adenosine Kinase is one of the most important enzymes involved in this pathway.
Mechanism:
Asp318 acts as a base to deprotonate the O5' hydroxyl group of adenosine to promote its nucleophilic attack to the terminal phosphate of ATP to yield the products. The transition state is stabilised by Arg136, which interacts with the gamma-phosphate of ATP, and Mg2+ ion, which interacts with alpha- and beta-phosphates of ATP to neutralise the charges of ATP.
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Found by:
Literature reference 
PsiBLAST alignment on 1lio

ResidueChainNumberUniProt numberFunctional part FunctionTargetDescription
999 0
It interacts with the alpha- and beta-phosphate groups of ATP, neutralising the charges, to stabilise the transition state.
Evidence from paper Evidence concerns Evidence type
PubMed ID 10801355 Current protein Ligand is essential for catalysis

ResidueChainNumberUniProt numberFunctional part FunctionTargetDescription
ARGA 136 136Sidechain
ElectrostaticTransition state
It interacts with the gamma-phosphate of ATP to stabilise the transition state.
Evidence from paper Evidence concerns Evidence type
PubMed ID 10801355 Current protein Conservation of residue
PubMed ID 10801355 Current protein Structural similarity to homologue of known mechanism
PubMed ID 10801355 Current protein Residue is positioned appropriately (ligand position known)

ResidueChainNumberUniProt numberFunctional part FunctionTargetDescription
ASPA 318 318Sidechain
Acid/baseSubstrate
It acts as a base to deprotonate the O5' hydroxyl group of adenosine to promote its nucleophilic attack on the terminal phosphate group of ATP.
Evidence from paper Evidence concerns Evidence type
PubMed ID 10801355 Current protein Residue is positioned appropriately (ligand position known)
References:
1
Crystal structures of Toxoplasma gondii adenosine kinase reveal a novel catalytic mechanism and prodrug binding.
M. A. Schumacher and D. M. Scott and I. I. Mathews and S. E. Ealick and D. S. Roos and B. Ullman and R. G. Brennan
J Mol Biol 298, (5) 875-93, (2000).
10801355
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