The X-Gal (5-bromo-4-chloro-3-indolyl-beta-D-galacto-pyranoside) is an inert chromogenic substrate for beta-galactosidase which hydrolyzes X-Gal into colorless galactose and 4-chloro-3-brom-indigo, forming an intense blue precipitate. It is provided as a convenient 20 mg/ml concentrate in DMF, ready for dilution into culture medium or appropriate buffers.
This product is commonly used to distinguish between recombinants and nonrecombinants by lacZ α-complementation with appropriate vectors and hosts. Induction of the lacZ gene with IPTG leads to the hydrolysis of X-Gal and to the development of blue colonies.
2. Physical State—Liquid
Shelf Life：Store at -20°C for 1 year.