Demonstration of sulfhydryl and disulfide groups by a fluorescent maleimide procedure

Several fluorescent maleimide compounds were evaluated as possible substitutes for N-(4-aminophenyl)maleimide in the histochemical procedures developed by Sippel (1973, 1978a, b, 1980) for the demonstration of sulfhydryl and disulfide groups. The brightest and most selective fluorescence was obtained by using N-(7-dimethylamino-4-methylcoumarinyl)maleimide (DACM), although both eosin-5-maleimide and fluorescein-5-maleimide could also be used if adequate control preparations were made.