X-Gal; 5-bromo-4-chloro-3-indolyl-ß-D-galactopyranoside

The chemical name of X-Gal is X-Gal is 5-Bromo-4-chloro-3-indolyl β-D-galactopyranoside, which is a chromogenic substrate for β-galactosidase and produces an insoluble blue color precipitate by cleaving X-Gal. The insoluble blue color precipitate can easily be detected visually over background. X-Gal is commonly used in molecular biology cloning application to detect the activity of β-galactosidase and in conjunction with IPTG for blue-white bacterial colony screening. It is also used to detect the insertion of foreign DNA into the lacZ region of a plasmid DNA. Insertion of DNA into the lacZ region results in the loss of β-galactosidase activity and the bacteria cells that retain active β-galactosidase will result in characteristic blue colonies. Successful disruption of the lacZα gene disrupts the α-complementation of the β-galactosidase gene and the precipitate does not form, resulting in white colonies.

Major Applications:

• X-Gal is used in immune-histochemistry applications.
• It is also the substrate of choice for blue-white selection of recombinant bacterial colonies with the lac⁺ genotype.

CAS No.:                     7240-90-6

Molecular weight:        408.63 g/mol

Molecular Formula:     C₁₄H₁₅BrClNO₆

Purity:                          Greater than 99% (HPLC)

Grade:                         Molecular Biology Grade

Solubility:                    Clear (2% in DMF)

Biological Activity:       Blue color with Lambda, pUC, and M13

Storage/Handling:       Store at -20°C. Protected from Light.

PubChem Chemical ID: 619018

InChI Key:                   OPIFSICVWOWJMJ-AEOCFKNESA-N