Enzyme - Adenosine kinase

Alternative Name(s)

There are no alternative names for this Enzyme

Catalytic Activity

denosine + ATP = ADP + AMP + H(+)


There are no Cofactors for this Enzyme

Reaction Mechanism

    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, Toxoplasma gondii cannot synthesise purine bases de novo, so enzymes of the Toxoplasma gondii purine salvage pathway are required for parasite survival. Adenosine Kinase is one of the most important enzymes involved in this pathway. Therefore it represents an attractive target for drugs which attack this highly dangerous parasite.

    Upon adenosine binding, a conserved dipeptide Gly68-Gly69 at the active site triggers a rigid-body rotation of 30 degrees of the lid domain, resulting in occlusion of the adenosine and the gamma-phosphate of ATP from the solvent. The reaction is ordered with adenosine binding first. This binding results in structural changes which are required in order for ATP to bind. The binding of ATP induces the formation of an anion hole, which completes the structural requirements for catalysis [PMID:10801355]. Asn223 and Glu226 are important in magnesium ion and phosphate binding.

    The 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 beta and gamma phosphate groups are in an eclipsed conformation, which results in a sterically and energetically strained state, thus aiding in pentavalent transition state formation [PMID:10801355] which is stabilised by Arg 136 and a Mg(II) ion.

    Catalytic Residues
    AA Uniprot Uniprot Resid PDB PDB Resid
    Asp Q9TVW2 318 1lij 318
    Arg Q9TVW2 136 1lij 136
    Step Components

    overall product formed, proton transfer, overall reactant used, bimolecular nucleophilic substitution, native state of enzyme regenerated, inferred reaction step

    Step 1.

    Asp318 deprotonates the -CH2-OH group of the adenosine substrate, which initiates a nucleophilic substitution against the gamma-phosphate of ATP. The adenosine 5'-hydroxyl group is positioned optimally for an in-line nucleophilic attack on the ATP gamma-phosphate atom. Asp318 is the likely candidate for proton abstraction of the 5'-hydroxyl group.

    Step 2.

    Water deprotonates Asp318 in an inferred return step.


    The products of the reaction.

Reaction Parameters

There are no kinetic parameters information for this Enzyme

Associated Proteins

Protein name Organism
Adenosine kinase Mycobacterium tuberculosis (strain ATCC 25177 / H37Ra)
Adenosine kinase 2 Mouse-ear cress
Adenosine kinase 1 Mouse-ear cress
Uncharacterized protein - B3LZN2 Fruit fly
PfkB kinase family protein Mycoplasma haemocanis (strain Illinois)