Switching protein metalloporphyrin binding specificity by design from iron to fluorogenic zinc.

Metalloporphyrins play important roles in areas ranging from biology to nanoscience. Using computational design, we converted metalloporphyrin specificity of cytochrome b from iron to fluorogenic zinc. The new variant had a near total preference for zinc representing a switch in specificity, which greatly enhanced the negligible aqueous fluorescence of free ZnPP in vitro and in vivo.