Metal-ion mediated interaction of luciferase with tetraiodofluorescein.

Tetraiodofluorescein binds to luciferase in an apparently competitive manner, according to kinetic inactivation studies. Among the metal ions studied, Cu2+ and Ni2+ are the only two of the first row transition series that enhance enzyme inactivation by the dye. Mg2+, Co2+ and Mn2+ seem to have a protective effect whereas Zn2+ prevents enzyme inactivation and even enhances its activity. Luciferase bound to tetraiodofluorescien-Sepharose via a metal ion can subsequently be eluted with appropriate ligands. Luciferase was found to be sensitive to the spacer geometry of immobilized tetraiodofluorescein.