Zinc Probes

Zinc is the second most abundant transition metal (after iron) in living organisms. Many zinc-dependent enzymes and transcription factors are known. Its central role in cellular processes such as gene expression, apoptosis, enzyme regulation and neurotransmission suggests that Zn²⁺ is a major regulatory ion in cell metabolism.

However, compared to other cations like Ca²⁺, Na⁺, K⁺, relatively little is known about the cellular regulation of Zn²⁺. Most of the Zn²⁺ abundant in eukaryotes is tightly bound. With respect of the cellular regulation of Zn²⁺, the “free” (chelatable) Zn²⁺ is of special interest. “Free” Zn²⁺ is found in relatively high concentrations in the brain, pancreas and spermatozoa. Several tools for measuring chelatable Zn²⁺ in living cells have been established to clarify its physiological significance. Similar to the well-established probes for intracellular Ca²⁺ such as Fura-2, a range of fluorogenic Zn²⁺-probes have been developed. Newer probes can be excited in the visible range to avoid cell damage and high background fluorescence.