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. Author manuscript; available in PMC: 2019 Dec 11.
Published in final edited form as: Biochemistry. 2019 Nov 21;58(49):4935–4949. doi: 10.1021/acs.biochem.9b00745

Figure 6.

Figure 6.

The [4Fe-4S]2+ cluster of EcFeoC is rapidly oxygen sensitive. A. Representative time course spectra of cleaved, anaerobically reconstituted EcFeoC reacting with air-saturated buffer. Spectra were taken every 6 s (black, dotted) immediately after buffer mixing until reactivity stopped (≈ 5 min). The [4Fe-4S]2+ spectral features (goldenrod) are rapidly lost and the appearance of the [2Fe-2S]2+ spectral features rapidly appear (purple). The inset represents the plots of the two species before (goldenrod) and after (purple) reaction. The sample was in 50 mmol/L MOPS buffer, pH 7.5, 150 mmol/L NaCl, and 1 mmol/L TCEP at room temperature. B. Representative plot of the kinetic decay of the absorbance feature at 400 nm (closed circles), characteristic of the [4Fe-4S]2+ cluster, and its fitted simulation (black dashed line), revealing a kobs of (0.037 ± 0.010) s−1 and a t½ of (19 ± 4.8) s when averaged over three replicates.