X-gal (5-Bromo-4-chloro-3-indolyl-β-galactopyranoside) is the most widely used chromogenic substrate for β-galactosidase. Enzyme hydrolysis of the substrate yields a dark blue colored precipitate (maximum absorbance 615 nm).White solid soluble in DMSOStore desiccated at -20°C and protect from lightC14H15BrClNO6MW: 408.6[7240-90-6]