Bioorganic & Medicinal Chemistry 1993-08-01

X-Neu5Ac: a novel substrate for chromogenic assay of neuraminidase activity in bacterial expression systems.

I Fujii, Y Iwabuchi, T Teshima, T Shiba, M Kikuchi

Index: Bioorg. Med. Chem. 1 , 147, (1993)

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Abstract

A chromogenic substrate 1, 5-bromo-4-chloroindol-3-yl 5-acetamido-3,5-dideoxy-alpha-D-glycero-D-galacto-2-nonulopyranosidon ic acid (X-Neu5Ac), has been synthesized to facilitate the screening of bacterial colonies or plaques for the detection of either natural or mutant neuraminidase activity. Substrate 1 was hydrolyzed by neuraminidase isolated from Clostridium perfringens to release a halogenated indol-3-ol 2 that undergoes rapid aerobic oxidation to form the dark blue pigment, 5,5'-dibromo-4,-4'-dichloroindigo 3. 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 1 can be useful to screen for bacterially-encoded enzyme production directly on agar plates.