Toxicity of hemoglobin derivatized with oxidized adenosine triphosphate against tumoral human cells

. Adenosine triphosphate (ATP) has a high affinity for the organic phosphate binding site of hemoglobin (Hb), affecting the affinity for oxygen. Periodate-oxidized-ATP (oATP) behaves as an affinity tag for several enzymes that use ATP as a substrate and has the ability to form intermolecular aldimine bonds by reaction with free amino groups on proteins. Due to its unique structure, oATP has been used to produce structural and functional modifications of Hb to obtain a compound with a low affinity for oxygen that could be used as a blood substitute. However, the oATP-Hb derivative was shown to present a notable increase in pro-oxidative reactivity compared to Hb in vitro, and accordingly exhibited toxicity in in vivo studies. This pro-oxidant reactivity was alleviated by crosslinking Hb with bovine serum albumin (BSA) in an oATP-Hb-BSA copolymer. We now show that oATP and oATP-Hb-BSA display high-affinity toxicity towards cancer cells, and may hence deserve further investigation as adjuvants in anti-cancer therapy.