FIG. 2.

Inhibition of malarial parasite TS by folate-based inhibitors. (A) Comparison of enzyme inhibition by 1843U89 and D1694. The substrates were used at a subsaturating concentration of 2 μM for dUMP and 35 μM for methylenetetrahydrofolate (MTHF). Each assay was performed with 20 U of TS activity. (B) Double-reciprocal plot to assess inhibition of malarial parasite TS by various amounts of 1843U89 (1.25, 2.5, 5, and 10 nM) in the presence of a fixed concentration of 50 μM dUMP and between 25 and 200 μM methylenetetrahydrofolate. (C) Secondary plot to estimate the strength of binding between 1843U89 and malarial parasite TS.