The BODIPY® FL chloramphenicol substrate in the FAST CAT® Chloramphenicol Acetyltransferase Assay Kit has a K_m for purified CAT of 7.4 µM and a V_max of 375 picomoles/unit/minute values that are similar to those of ¹⁴C-labeled chloramphenicol. To perform the assay, cell extracts are simply incubated with BODIPYR() FL chloramphenicol and acetyl coenzyme A. The products and remaining substrate are extracted and separated by thin-layer chromatography (TLC). The brightly fluorescent, well-resolved spots can be immediately visualized with a hand-held UV lamp or quantitated with a laser scanner or CCD camera.