Chemistry

Finding the Missing Zinc

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Science  09 Jun 2000:
Vol. 288, Issue 5472, pp. 1707
DOI: 10.1126/science.288.5472.1707a

Divalent cations such as calcium and magnesium play critical biochemical roles as cofactors and in cell signaling, and specialized dyes and probes have been developed to determine their free intracellular concentrations. Although zinc (Zn2+) also plays important roles as a cofactor as well as in programmed cell death and neurotransmission, readily determining cellular concentrations of unchelated Zn2+ has proven more difficult, in part because Zn2+, even when bound to a molecule, can still bind to some of its fluorescent dyes. Dyes currently in use or that have been considered have drawbacks that include low affinity, poor optical properties, or the need for microinjection into cells or ultraviolet excitation. Walkup et al. now report on a high-affinity, membrane-permeable fluorescent dye, Zinpyr-1, whose emission at 507 nm, which can be excited at visible wavelengths, increases by more than a factor of 3 when free Zn2+ is present. Preliminary studies in Cos-7 cells show targeting (Golgi and acidic compartments) similar to that of dyes currently in use.—PDS

J. Am. Chem. Soc., in press.

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