5-Bromo-4-chloro-3-indolyl N-acetyl-a-D-neuraminic acid sodium salt

X-NeuNAc is a chromogenic substrate for neuraminidases, which are enzymes that cleave glycosidic linkages of neuraminic acids. Upon hydrolysis by neuraminidase, halogenated indol-3-ol is released and undergoes rapid aerobic oxidation to the dark blue pigment 5,5?-dibromo-4-4?-dichloroindigo, which can be used to quantify neuraminidase activity.

X-NeuNAc, also known as CB1339 and X-Neu5Ac, is a novel substrate for chromogenic assay of neuraminidase activity in bacterial expression systems. X-NeuNAc can be used to facilitate the screening of bacterial colonies or plaques for the detection of either natural or mutant neuraminidase activity. Preliminary kinetic studies indicate that this compound is a good substrate (Km 0.89 x 10(-3) M) for neuraminidase and is quite stable under identical conditions in the absence of enzyme. These results suggest that X-Neu5Ac can be useful to screen for bacterially-encoded enzyme production directly on agar plates.

Chromogenic substrate for neuraminidase yielding a blue precipitate upon cleavage.