5-Bromo-4-chloro-3-indoxyl-β-D-galactopyranoside

CAS: 7240-90-6

Ref. 3D-B-7150

Product Information

• Name: 5-Bromo-4-chloro-3-indoxyl-β-D-galactopyranoside
• Synonyms: X-beta-D-galactoside EB06680
• Brand: Biosynth
• Description: X-Gal is a chromogenic substrate for β-galactosidase, yielding a blue precipitate. X-Gal is an indicator for coliforms in culture media, as well as for the detection of coliforms (E. coli) in municipal water supplies and food products. X-Gal can be used in conjunction with the inducer IPTG, which binds and inhibits the lac repressor thus inducing β-galactosidase expression. X-Gal is the substrate of choice for blue-white selection of recombinant bacterial colonies with the lac+ genotype.Upon hydrolysis, X-Gal yields a localized, insoluble, blue precipitate, making it exceptionally useful in blotting, immunocytochemical, and ELISA assays. 5-Bromo-4-chloro-3-indoxyl-beta-D-galactopyranoside (X-beta-D-galactoside, X-Gal) is a chromogenic indicator for beta-galactosidase activity. The colorless product is cleaved by lactose-utilizing bacteria in liquid media or on agar plates and yields a blue-green colored precipitate.X-Gal can also be used as a detecting agent for beta-galactosidase activity in reporter gene assays or for identification of positive transformants on agar plates when using the α-complementation approach. Color formation is due to dimerization and oxidation of 5-bromo-4-chloro-3-hydroxyindole which results from enzymatic cleavage of X-Gal. The reaction proceeds only in the presence of oxygen, i.e. in aerobic cultures. Well detectable color bacterial colonies or liquid cultures is obtained within 16-48 h. In the presence of purified beta-galactosidase, color develops within minutes to a few hours.

Chemical properties

• Molecular weight: 408.64 g/mol
• Formula: C₁₄H₁₅BrClNO₆
• Purity: Min. 99.0 Area-%