Mechanism-Based Inhibitors: Development of a High Throughput Coupled Enzyme Assay to Screen for Novel Antimalarials

Identifying potent enzyme inhibitors through a robust HTS assay is currently thought to be the most efficient way of searching for lead molecules. We have developed a HTS assay that mimics a crucial step in an essential metabolic pathway, the purine salvage pathway of the malarial parasite Plasmodium falciparum. In this assay we have used purified recombinant enzymes: hypoxanthine guanine phosphoribosyl transferase (HGPRT) and inosine monophosphate dehydrogenase (IMPDH) from the malarial parasite and the human host, respectively. These two enzymes, which work in tandem, are used to set up a coupled assay that is robust enough to meet the stringent criteria of an HTS assay. In the first phase of our screen we seem to have identified novel inhibitors that kill the parasite by inhibiting the salvage pathway of the parasite.