New Fluorogenic Reagent Having Halogenobenzofurazan Structure for Thiols: 4-(Aminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole

Abstract

4-(Aminosulfonyl)-7-fluoro-2,1,3-benzoxadlazole (ABD-F) has been synthesized as a new fluorogenic reagent for thiols. Its reaction rate to homocysteine Is over 30 times faster than that with ammonium 7-fluoro-2,1,3-benzoxadlazole-4-sulfonate (SBD-F). The fluorogenic reaction to thiol was completed quantitatively In 5 min at 50 °C and pH 8.0. Alanine, proline, and cystine did not react under the same conditions. The fluorescence Intensity of the fluorophor was pH dependent with the highest at pH 2. The ABD-thiols obtained by the prelabeling technique were separated and detected by reversed-phase HPLC. The detection limits (S/N = 3) for cysteine, glutathione, N-acetyicysteine, homocysteine, and cysteamine were 0.6, 0.4,1.9, 0.5, and 0.5 pmol, respectively. © 1984, American Chemical Society. All rights reserved.