Hypoxanthine guanine phosphoribosyltransferases (HGPRTs) catalyze the conversion of 6-oxopurine bases to their respective nucleotides, the phos-phoribosyl group being derived from phosphoribosyl pyrophosphate. RecombinantPlasmodium falciparumHGPRT, on purification, has negli-gible activity, and previous reports have shown that high activities can be achieved upon incubation of recombinant enzyme with the substrates hypo-xanthine and phosphoribosyl pyrophosphate [Keough DT, Ng AL, Winzor DJ, Emmerson BT & de Jersey J (1999)Mol Biochem Parasitol98, 29–41; Sujay Subbayya IN & Balaram H (2000)Biochem Biophys Res Commun 279, 433–437]. .
