Chloramphenicol Acetyltransferase (CAT) Reporter Gene Activity Detection Kit

One of the most widely used reporter genes in mammalian expression systems is chloramphenicol acetyltransferase (CAT) from Escherichia coli. Mammalian cells have minimal CAT activity, resulting in high signal-to-background ratios for this reporter gene assay. Conventional CAT assays use a radioactive substrate and measure acetylated chloramphenicol. This carries all the disadvantages of radioactive assays plus another that is peculiar to the CAT reaction. Chloramphenicol has two free hydroxyl groups, but only the 3-OH is acetylated by CAT. The 3-acetate can rearrange to the 1-position non-enzymatically, and to the extent that it does, the 3-OH is open for further acetylation. The result is that three products are produced: two monoacetates and a diacetate. In addition, because the transacetylation is slow, the quantity of products is not a true measure of the CAT activity.

The BODIPY-labeled substrate and product are covered by U.S. Patent Nos. 5,262,545 and 5,364,764.