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. Author manuscript; available in PMC: 2020 Sep 18.
Published in final edited form as: J Am Chem Soc. 2019 Sep 10;141(37):14510–14514. doi: 10.1021/jacs.9b06093

Figure 1.

Figure 1.

Substrate-triggered, [O2]-dependent, rapid formation of an absorbing, on-pathway intermediate in the reaction of UndA-Fe2(II/II) with O2. (A and B) Absorption spectra acquired after rapid mixing at 5 °C of a solution containing 0.30 mM UndA, 0.54 mM Fe(II) (1.8 equiv), and either 0 mM (A) or 1.0 mM (B) LA with an equal volume of O2-saturated buffer (~1.8 mM O2). (C) Change in absorbance at 550 nm (ΔA550nm) versus time after mixing of the same protein reactant solution as in B with an equal volume of buffer containing O2 at the concentrations indicated in the legend. (D) Comparison of the ΔA550nm amplitudes (differences between maximum and minimum values) and quantities of LA consumed [relative to a reaction with no added Fe(II)] in analogous reactions with varying equivalencies of Fe(II):UndA in the protein solution. Details of the reactions and the procedure for LA quantification are provided in the Supporting Information.