A perspective essay on the use of Ga³⁺ as a proxy for Fe³⁺ in bioinorganic model studies and its successful use for therapeutic purposes.

The use of Ga³⁺ as a structural mimic for Fe³⁺ in model bioinorganic investigations is usually based on a common assumption that Ga³⁺ and Fe³⁺ should form bioligand complexes of similar stabilities due to their similar charge/radius ratio (z/r). However, the literature survey presented here is contrary to this notion, showing that under laboratory conditions often Ga³⁺ forms weaker bioligand complexes than Fe³⁺in aqueous medium. We hypothesize that this is because Ga³⁺ is more aquaphilic than Fe³⁺ as suggested by their relative heats of hydration (ΔH_hyd). The successful use of Ga³⁺ as a therapeutic agent is also briefly reviewed, showing this success often stems from the redox inertness as well as different pharmacokinetics of Ga³⁺ than Fe³⁺, but similar metabolic pathways as Fe³⁺ in human serum.

Duke Scholars

Author Alvin L. Crumbliss Chemistry