Figure 5. X-band EPR spectra of wt and βS188A MoFeP after oxidation and soaking with heterometals collected at 4 K.

(a) IDS-oxidized wt Av MoFeP (top) soaked with ⁵⁷Fe²⁺, Co²⁺, Ni²⁺, and Ga³⁺ (top to bottom). (b) IDS-oxidized βS188A Av MoFeP (top) soaked with ⁵⁷Fe²⁺, Co²⁺, Ni²⁺, and Ga³⁺ (top to bottom). Reconstitution with ⁵⁷Fe²⁺, Co²⁺, and Ni²⁺ resulted in new features in the g ≈ 5 region. All metal-treated βS188A samples had features in the g ≈ 2 region that closely resembled those for the oxidized βS188A species, but the features varied in intensity. Oxidized wt and βS188A spectra without added metals (top) are reproduced from reference 19 for comparison.