AG Scientific X-GAL, 1 G

X-Gal is commonly used in molecular biology in regards to cloning applications. First synthesized in 1964, this organic compound contains galactose, which is also found in casein, yogurt, and milk, as well as certain dairy-free products.

An analog of lactose, X-Gal is hydrolyzed by the β-galactosidase enzyme, resulting in 5,5-dibromo-4,4-dichloro-indigo -- an insoluble blue precipitate. This indicates enzymatic activity. For example, X-Gal can be used in molecular biology to detect genetic activity in cells and tissues.

Commonly used in blue/white screening, X-Gal yields a visual indication regarding the cellular expression of a functional β-galactosidase enzyme. In turn, key recombinant colonies can be easily identified and then cultured.