Fig 9. Mn²⁺ titrations of MntC bound to the monoclonal antibodies.

The titrations were monitored by ITC, as described in “Materials and Methods”. Black symbols and lines—Mn²⁺ titration of the isolated MntC (control), green symbols and lines—Mn²⁺ titration of MntC bound to mAB 305-72-5, blue symbols and lines—Mn²⁺ titration of MntC bound to mAB 305-101-8, red symbols—Mn²⁺ titration of MntC bound to the Fab fragment of mAB 305-78-7. Binding stoichiometry in all experiments (except for MntC bound to Fab 305-78-8) was 0.42–0.49 Mn²⁺ ions bound per molecule of MntC, consistent with the suggestion that recombinant MntC is partially occupied by an irreversibly bound metal[4]. Binding enthalpies were also comparable (~ -14 kcal/mol).