Redox properties of the calcium chelator Fura-2 in mimetic biomembranes

• Type: Article in International Scientific Journal
• Date: 2008

Authors

Rubin Gulaboski (Author) Other; Carlos M Pereira (Author) FCUP; Natalia N D S Cordeiro (Author) FCUP; Fernando F Silva (Author) FCUP; Markus Hoth (Author) Other; Ivan Bogeski (Author) Other

Journal

Title: Cell Calcium

Vol. 43 No. 6

Pages: 615-621

ISSN: 0143-4160

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 3 Citations

Scopus - 2 Citations

Scientific classification

FOS: Natural sciences > Biological sciences

Other information

Authenticus ID: P-003-YNW

DOI: 10.1016/j.ceca.2007.10.002

Abstract (EN): Fura-2 is one of the most commonly used fluorescent dyes to analyze the cytosolic Ca(2+) concentration ([Ca(2+)](i)) of living cells. Fura-2-dependent measurements of [Ca(2+)](i) are susceptible to changes of pH, reactive oxygen species concentration and membrane potential. Fura-2 is often loaded over the lipophilic cell membrane into the cytosol of a cell in its esterified form (Fura-2/AM) which is then cleaved by endogenous esterases. We have analyzed the electrochemical properties of Fura-2/AM and Fura-2 salt by cyclic voltammetry ("three-phase" and "thin-film" electrode methods). Using Fura-2/AM as a redox facilitator, we were able to mimic the transport of various ions across a lipophilic barrier. We show that Fura-2/AM in this biomimetic set-up can be reversibly oxidized in a single electrochemical step. Its redox reaction was highly proton sensitive in buffers with pH <= 6. At physiological pH of around 7.0, the oxidation of Fura-2/AM was coupled to an uptake of mono-anions across the liquid-liquid interface. The voltage-dependence of the redox cycle was sensitive to the free Ca(2+) concentration, either after de-esterification of Fura-2/AM, or when Fura-2 salt was used. The complex between Fura-2 and Ca(2+) ions is ionic (complexation occurs via the dissociated negative groups of Fura forms), while the redox transformations in Fura-2 occurs at the nitrogen atoms of the amino groups. Our results suggest that redox transformations of the Fura-2 forms do not affect the binding ability toward Ca(2+) ions and thus do not interfere with [Ca(2+)](i) measurements.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 7