LIFETIME-BASED FLUORESCENCE ENERGY-TRANSFER BIOSENSING OF ZINC

A new type of fluorescence transduction method for determining zinc in solution is described. The approach is based upon energy transfer fro m a fluorescent label on an enzyme, human carbonic anhydrase II, to a colored inhibitor which binds to zinc in the enzyme active site. If zi nc is present in solution, it binds to the apoenzyme, which in turn pe rmits the inhibitor to bind to the enzyme; the inhibitor is thus in cl ose proximity to the label on the enzyme and thereby quenches the labe l's fluorescence by Forster energy transfer with a concomitant reducti on of its lifetime, which is quantitated by phase fluorometry. (C) 199 5 Academic Press, Inc.