C14H15BrClNO6
M.W.: 408.63
Assay: 98.5% min.
Stock conc.: 2% (w/v) in dimethylformamide or DMSO.
 

    X-Gal is a chromogenic substrate of b-Galactosidase. It is used in conjunction with IPTG for detection of b-Galactosidase activity in bacterial colonies in a colorimetric assay to detect recombinants (white) from non-recombinants (blue). X-Gal is cleaved at the b 1-4 bond between galactose and the 5-Bromo-4-chloro-3-indolyl part of X-Gal by b-Glactosidase via hydrolysis.
    The cleavage of X-Gal results in the production of a water insoluble blue dichloro-dibromo-indigo precipitate at the site of enzymatic cleavage.

    In cloning strategies with vectors such as Lamda-11, M13mp18 and 19 and 19, pUC18 and 19, pUR222 the E.Coli lacZ gene is transformed to lac cells. After transformation the cells show b-Galactosidase activity in the presence of IPTG and X-Gal containing media. The insertion of a DNA fragment into the cloning sites of the lacZ gene results in the disruption of b-Galactosidase activity leading to the appearance of white colonies on X-Gal and IPTG containing media. Non recombinant cells produce a blue indigo dye on these media.