(A) The spectrum measured at 10 K and 10 μW power shows a mixture of spin-coupled [4Fe–4S] clusters (evidenced by the features at g ≈ 2.04, 1.97, and 1.89) and a [2Fe–2S] cluster (evidenced by the features at g ≈ 2.00, 1.95, and 1.92). (B) The spectrum measured at 40 K and 1 mW power shows the pure spectrum of a [2Fe–2S] cluster simulated using a rhombic g tensor (2.003, 1.953, 1.923) using g strain (0.012, 0.018, 0.015). At 40 K, the additional features observed at 10 K have been lifetime broadened, confirming that they arise from fast relaxing [4Fe–4S] clusters. All other EPR parameters are given in the methods. (C) EPR spectra of HydB isolated from native T. maritima are reproduced from Verhagen et al., 1999 for comparison. The close agreement between the spectrum in (A) and the upper spectrum in (C) and between the spectrum in (B) and the lower spectrum in (C) indicates that the same cohort of EPR-detectable iron–sulfur clusters is present in both preparations.
© 1999, Elsevier. Figure 1 - figure supplement 1C is reproduced from Figure 6 from Verhagen et al., 1999, with permission from Elsevier. It is not covered by the CC-BY 4.0 licence and further reproduction of this panel would need permission from the copyright holder.