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. Author manuscript; available in PMC: 2014 Jun 12.
Published in final edited form as: J Am Chem Soc. 2013 May 31;135(23):10.1021/ja401342s. doi: 10.1021/ja401342s

Figure 1.

Figure 1

EPR and Mössbauer spectra of Ec RNR before and after N3UDP-induced trapping of the product of forward radical translocation. (A) EPR spectra of uniformly 57Fe labeled α2β2 with TTP and in the absence (green) or presence (red) of N3UDP. Subtraction of the features of the unreacted Y122• (green) from the spectrum of the N3UDP-treated sample (red) yields the spectrum of the N• (blue). 4.2-K/53-mT Mössbauer spectra of uniformly 57Fe labeled (B), site 1 57Fe enriched (C) and site 2 57Fe enriched (D) α2β2 with TTP and in the absence (I) or presence (II) of N3UDP. The solid lines in I are simulations of the two quadrupole doublets (red and blue) of the resting (FeIII)2 cluster with parameters quoted in the text and the sum of the two doublets (black). The solid line in II is the spectrum from I scaled appropriately to remove the contribution of the unreacted cofactor, and subtraction of this contribution from II reveals the spectrum of the product of the forward radical translocation (III), which can be simulated with two quadrupole doublets (red and blue; parameters quoted in the text). The sum of the two quadrupole doublet simulations is shown as a black line. The spectrum in IV is the total difference of I-II and the solid line is a simulation of the difference spectrum as a sum of the four quadrupole-doublet components.