Patent ID: 7491545

Claim:
A method for quantitation of zinc ion in a sample comprising: i) disposing in said sample a donor fluorescent sulfonamide fluorophore and a carbonic anhydrase protein having conjugated thereto an acceptor fluorophore, wherein the binding of said donor fluorophore to the conjugated carbonic anhydrase is dependent upon the presence of zinc ion complexed to the conjugated carbonic anhydrase; ii) measuring the intensity of a fluorescence emission of the acceptor fluorophore upon excitation of the donor fluorophore at a first excitation wavelength; iii) measuring the intensity of a fluorescence emission of the acceptor fluorophore upon excitation of the acceptor fluorophore at a second excitation wavelength; iv) obtaining the ratio of the intensities measured in steps ii) and iii) and; v) relating the quantity of zinc ion in the sample to the ratio obtained in step iv).