4-Trifluoromethylumbelliferyl b-D-galactopyranoside

4-Trifluoromethylumbelliferyl ?-D-galactopyranoside is a chromogenic substrate that can be used to detect the presence of ?-glucuronidase and ?-galactosidase in a variety of organisms. This compound has been shown to be useful for the detection of bacteria such as E. coli, Salmonella, and Listeria monocytogenes. 4TFU has been shown to hydrolyze at pH values between 5 and 8. The reaction starts with a color change from yellow to blue at pH 5, which changes again to green at pH 8. The equivalence point for this substrate is at pH 6.4, where it produces an orange color.

Blue-green fluorogenic probe with higher fluorescence in the physiological pH range due to lower pKa. Suitable for the detection of LacZ without the need of a stop buffer treatment step for development of fluorescence.