Ferrocenoyl derivatives of alamethicin: redox-sensitive ion channels

Two redox-active C-terminal derivatives of alamethicin have been synthesized and their single-channels have been characterized. The reduced (Fe(II)) forms of ferrocenoyl-alamethicin (Fc-ALM) and 1'-carboxyferrocenoyl-alamethicin (cFc-ALM) were found to form voltage-dependent ion channels at cis positive potentials in planar lipid bilayers (PLB) with conductance characteristics similar to those of alamethicin. In situ oxidation of Fc-ALM in the PLB system produces a time-dependent elimination of channel openings. On the other hand, oxidation of cFc-ALM leads to the formation of shorter-lived channels.