Measurement of free Zn2+ ion concentration with the fluorescent probe mag-fura-2 (furaptra).
The fluorescent probe mag-fura-2, previously used to measure [Mg2+], can also be used to measure [Zn2+]. The peak in the excitation spectrum occurs at 323 nm for Zn2+, compared with 335 nm for Ca2+ and Mg2+. This allows simultaneous measurements of [Zn2+] and either [Ca2+] or [Mg2+], by using 3 excitation wavelengths. The dissociation constant for Zn2+ is 20 nM at pH 7.0-7.8, ionic strength 0.15 and 37 degrees C. This allows [Zn2+] to be measured in the range from 0.5 nM to 1 microM. Mag-fura-2 was used to measure [Zn2+] in Zn2+/albumin and Zn2+/histidine mixtures in a physiological buffer at 37 degrees C and pH 7.4. The data obtained enable one to formulate Zn(2+)-buffers for the 1 to 100 nM Zn2+ range.
Simons
T J
TJ
Biomedical Sciences Division, King's College, London, UK.
D000818:Animals; D001572:Benzofurans; D002118:Calcium / Q000032:analysis*; D005456:Fluorescent Dyes; D016257:Fura-2 / Q000031:analogs & derivatives*; D006639:Histidine; D006801:Humans; D007202:Indicators and Reagents; D008274:Magnesium / Q000032:analysis*; D010080:Oxazoles; D011485:Protein Binding; D012710:Serum Albumin, Bovine; D013050:Spectrometry, Fluorescence / Q000379:methods; D015032:Zinc / Q000032:analysis* / Q000097:blood
D001572:Benzofurans; D005456:Fluorescent Dyes; D007202:Indicators and Reagents; D010080:Oxazoles; C058776:2-(2-(5-carboxy)oxazole)-5-hydroxy-6-aminobenzofuran-N,N,O-triacetic acid; D012710:Serum Albumin, Bovine; D006639:Histidine; D008274:Magnesium; D015032:Zinc; D002118:Calcium; D016257:Fura-2