5-Bromo-4-chloro-3-indolyl a-D-galactopyranoside / X-alpha-Gal

X-alpha-D-Gal is a chromogenic substrate for alpha-galactosidase yielding a blue precipitate (X-alpha-Gal is a chromogenic substrate for yeast galactosidase (MEL1) and is used for detecting GAL4-based yeast two-hybrid interactions directly on agar). Used for species differentiation within the family Enterobacteriaceae and differentiation of Bifidobacteria species from Lactobacillus species (see references). Synonmys: 5-Bromo-4-chloro-3-indolyl a-D-galactopyranoside, X-α-Gal; X-alpha-Gal.

Other products that are used as a substrate for alpha or beta-Galactosidase:

M3225: 5-Bromo-3-indolyl-beta-D-galactopyranoside >
M3204: 5-Bromo-4-chloro-3-indolyl-β-D-galactopyranoside (X-Gal) >
M3205: 5-Bromo-4-chloro-3-indolyl-ß-D-glucopyranoside (X-Glu / X-Glc) >

References:
1. Aho S., Arffman A., Pummi T., Uitto J., A novel reporter gene MEL1 for the yeast two-hybrid system. Anal Biochem. 1997, 253, 270-2.
2. Chevalier P., et al., X-alpha-Gal-base medium for simultaneous enumeration of bifidobacteria and lactic acid bacteria in milk. J. Microbiol. Methods 1991, 13, 75.
3. Gossrau R., Lojda Z., Histochemical detection of alpha-D-galactosidase with 5-Br-4-Cl-3-indoxyl alpha-D-galactoside. Acta Histochem. 1989, 85, 213-22.
4. Perry J.D., Ford M., Taylor J., Jones A.L., Freeman R., Gould F.K., ABC medium, a new chromogenic agar for selective isolation of Salmonella spp. J. Clin. Microbiol. 1999, 37, 766-8.