X-GlcA cyclohexylammonium salt

X-GlcA, 5-Bromo-4-chloro-3-indolyl-ß-D-glucuronic acid is a substrate for ß-D-Glucuronidase (GUS) encoded by the gusA gene. The substrate is used as a qualitative histochemical marker of specific GUS expressions in cells and tissue. X-GlcA is cleaved by GUS at the ß1 glucuronic bond between glucuronic acid and the 5-Bromo-4-chloro-3-indolyl part of X-GlcA via hydrolysis. The enzymatic cleavage of X-GlcA results in the precipitation of a water insoluble blue dichloro-di-bromo-indigo precipitate. Color formation requires three separate reactions. After enzymatic turnover, the released in-doxyl derivative dimerises and is sub-sequently oxidized to the final indigo dye.