N-dansyl-S-nitrosohomocysteine a fluorescent probe for intracellular thiols and S-nitrosothiols

The fluorescence emission spectrum of N-dansyl-S-nitrosohomocysteine was en hanced similar to 8-fold upon removal of the NO group either by photolysis or by transnitrosation with free thiols like glutathione. The fluorescence enhancement was reversible in that it could be quenched in the presence of excess S-nitrosoglutathione. Attempts were then made to utilize N-dansyl-S- nitrosohomocysteine as an intracellular probe of thiols/S-nitrosothiols. Fl uorescence micro sco py of fibro blasts in culture indicated that intracell ular N-dansyl-S-nitrosohomocysteine levels reached a maximum within 5 min. N-Dansyl-S-nitrosohomocysteine fluorescence was directly proportional to in tracellular GSH levels, directly determined with HPLC. N-Dansyl-S-nitrosoho mocysteine preloaded cells were also sensitive to S-nitrosoglutathione upta ke as the intracellular fluorescence decreased as a function of time upon e xposure to extracellular S-nitrosoglutathione. (C) 1999 Elsevier Science B. V. All rights reserved.