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 currentl y 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 metab olic pathway, the purine salvage pathway of the malarial parasite Plasmodiu m falciparum. In this assay we have used purified recombinant enzymes: hypo xanthine guanine phosphoribosyl transferase (HGPRT) and inosine monophospha te dehydrogenase (IMPDH) from the malarial parasite and the human host, res pectively. These two enzymes, which work in tandem, are used to set up a co upled 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 in hibitors that kill the parasite by inhibiting the salvage pathway of the pa rasite.