A novel fluorogenic reagent for thiols: ammonium 7-fluorobenzo-2-oxa-1,3-diazole-4-sulfonate

Ammonium 7-fluorobenzo-2-oxa-1,3-diazole-4-sulfonate (SBD-F) was newly synthesized as a fluorogenic reagent for thiol compounds. Its reactivity to glutathione is superior to its 7-chloro analog, SBD-Cl. The optimal reaction condition was selected at 60 degrees C and pH 9.5 for 1 h. The detection limits for glutathione, coenzyme A, cysteamine, homocysteine, N-acetylcysteine, cysteine, and D-3-mercaptomethylpropanoyl-L-proline (captopril) were 100, 120, 160, 330, 390, 3600, and 150 pmol/ml, respectively. Proline and alanine did not give fluorescence under this condition.