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. Author manuscript; available in PMC: 2015 Oct 1.
Published in final edited form as: J Inorg Biochem. 2014 Jun 27;139:93–105. doi: 10.1016/j.jinorgbio.2014.06.011

Fig. 9. Progressive power-dependent EPR spectra of the radical intermediates formed in the reaction between ferrous iNOSox and oxygen.

Fig. 9

The reaction was identical to that described in Fig. 8. EPR spectra were recorded at microwave powers ranging from 0.025–100 mW with 3 dB increment for 40–50 µM iNOSox with equimolar concentration of BH4 and 500 µM L-Arg present (A) or with BH4 alone (B) or with L-Arg alone (C) at 115 K. Almost identical EPR spectra shown in (C) were obtained for iNOSox in the absence of both BH4 and L-Arg (data not shown). Difference spectra obtained by subtracting of 40% spectra (C) from spectra (B) to maximally remove the g= 2.005 sharp dip signal are shown at panel (D). Spectra D are very similar to typical EPR spectra of BH4 radical of iNOSox (A). Vertical dash lines are visual guides. Insets in (B) and (C) are plots to obtain the half-saturation power via non-linear regression to Equation 1. Symbols are the data and lines are the fit.