Figure 5

HQBA is an iron chelator. (a) Mixture of 10 μM HQBA with varying concentrations of FeCl₂ dose dependently reduced the absorbance of HQBA at 245 nM. (b) Stoichiometry of Fe²⁺ binding is derived from plotting 1/OD₂₄₅ versus [Fe²⁺]/[HQBA]. The intersection of slopes for Fe²⁺ saturated and unsaturated HQBA absorbance indicates that two molecules of HQBA bind one Fe²⁺ ion. (c) Absorbance (Abs) at 245 nM of 10 μM HQBA with equimolar concentrations of various transition metals in the same series as Fe²⁺ indicates that it chelates Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺, but not Mn²⁺.