Fig. 5. ESI-MS analysis of RirA following low iron-mediated cluster conversion. Positive ion mode ESI-TOF native mass spectra of ∼21 μM [4Fe–4S] RirA in 250 mM ammonium acetate pH 7.35 following treatment with 1 mM EDTA for 2.5 h. Deconvoluted spectrum in the (A) monomer and (B) dimer mass regions. ESI-MS data for RirA prior to the addition of EDTA are shown in Fig. 3.
