Fig. 2. Structures of the mitochondrial iron chelator–peptides (“compounds 2 and 13”). The structures of the compounds used in this study are depicted with their ionized functions at pH 7.4. (a) The three catechol functions (circled) form the iron-binding moieties which together bind iron as a hexadentate chelator for compound 2. (b) Likewise, the hydroxypyridinone chelating moiety in compound 13 is circled and the fluorescent probe dansyl is coloured in red.