The partial purification and characterization of adenosine kinase from Entamoeba histolytica

Axenically grown Entamoeba histolytica was found to contain adenosine kinase. This organism lacks de novo purine biosynthetic pathways. Adenosine kinase provides the amoeba with a method for salvaging adenosine from ingested nucleosides or from degraded nucleotides. Adenosine kinase was purified 64-fold, by chromatography on Sephacryl S-200, DEAE-cellulose, and (C-8)-adenosine-agarose. The latter separated it from amebal adenylate kinase. Adenosine kinase has a molecular weight of 38,000 and requires glycerol for stability. It utilizes adenosine triphosphate to phosphorylate adenosine, and 7-deazaadenosine (tubercidin), but adenine 9-beta-D-arabinofuranoside (ara-A) is not detectably phosphorylated. It requires Mg++ as a cofactor.