5-Bromo-3-indolyl-β-D-galactopyranoside (Bluo-Gal) is a cell-permeable chromogenic substrate for β-galactosidase.1 Upon enzymatic hydrolysis, it generates an indigo-colored precipitate that can be used to measure β-galactosidase activity. Bluo-Gal has been used to detect the expression of β-galactosidase in muscle from transgenic mice expressing E. coli lacZ, the gene that encodes β-galactosidase.
1.Gioglio, L., de Angelis, M.G.C., Boratto, R., et al.An improved method for β-galactosidase activity detection on muscle tissue. A light and electron microscopic studyAnn. Anat.184(2)153-157(2002)