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. Author manuscript; available in PMC: 2020 Jun 1.
Published in final edited form as: J Am Chem Soc. 2020 Mar 17;142(13):6018–6029. doi: 10.1021/jacs.9b11454

Figure 4.

Figure 4.

Fe2+enhances sulfur transfer from IscS to IscU. Time-resolved acid-quench (1% formic acid) denaturing MS experiments were used to track sulfur accumulation on IscU after mixing apo–IscU (75 μM) with IscS (15 μM), L-cysteine (300 μM), and various concentrations of ferrous acetate. Deconvoluted zero charge MS spectra are shown for monomeric IscU using (A) 0 μM and (B) 400 μM ferrous acetate after a reaction time of 3 min. (C) Total accumulated sulfur adducts per IscU are displayed as a function of time. The inset shows the early time points overlaid with linear regression fits (dashed lines). The error bars represent replicate errors (n = 3).