Applications
It is a substrate for beta-galactosidase, which cleaves the glycosidic bond to give 5-bromo-4-chloro-3-hydroxy-1H-indole, which immediately dimerises to give an intensely blue product. It is also used to detect activity of this enzyme in histochemistry and bacteriology. It is employed as a colorless, endogenous or exogenous pigment precursors that may be transformed by biological mechanisms into colored compounds. They are used in biochemical assays and in diagnosis as indicators, particularly in the form of enzyme substrates. X-Gal is the substrate of choice for blue-white selection of recombinant bacterial colonies with the lac+ genotype.

Solubility
Soluble in 100 mM in DMSO.

Notes
Moisture & Light sensitive. Store away from oxidizing agents, heat, water/moisture and light. Store under inert gas. Keep the container tightly closed and place it in a cool, dry and well ventilated condition.