FIG. 1.

CFHCS design. Compounds dissolved in DMSO are pin transferred to a 384-well microtiter plate containing a weakly basic hemin solution. Crystallization is catalyzed by the addition of 9.7 M acetate solution and incubation at 60°C for 2 h. A 14% pyridine solution is added to each well to identify wells in which heme crystallization is inhibited. Pyridine coordinates with the free iron centers of uncrystallized heme molecules, causing an increased absorbance at 405 nm. Supernatant from the assay plate is transferred to a new 384-well microtiter plate to eliminate interference from crystalline β-hematin solids, and absorbance is measured at 405 nm.