An immunoassay for the detection and quantitative determination of mycothiol

Mycothiol (MSH) is a glycosylated derivative of N-acetylcysteine that may have antioxidant functions in mycobacteria and other actinomycetes. To develop a highly specific assay for MSH, we capitalized on the selective binding of thiols to a maleimide residue linked to bovine serum albumin and employed affinity-purified polyclonal antibody and an enzyme-linked secondary antibody for detection. The assay was shown to be specific and to detect MSH at levels as low as 0.1 pmol when conducted in the form of a microtiter plate-based ELISA. A similar, nitrocellulose membrane-based immunoassay was shown to be useful for qualitative detection of MSH-producing bacterial colonies.