Figure 2.
RFQ-EPR spectra of (A) the intermediate X in R2-WT (relative ratio of X and Y122• 0.62:0.42), (C) in R2-Y122F/Y356F (98-100% X), and (E) the X-Y• (79%) diradical species, formed in the reaction of apo enzymes with FeII and O2, in comparison with EPR spectra of decayed intermediate X in R2-WT, R2-Y122F/Y356F, and R2-W48A (B, D, and F). The EPR spectra of decayed X were obtained by allowing the samples of X to thaw at room temperature for 10 minutes prior to freezing in liquid nitrogen. The spectrometer conditions for data acquisition were: microwave frequency 9.38 GHz, temperature 3.0 K, microwave power 10 μW, modulation frequency 100 KHz, modulation amplitude 4 G, and receiver gain of 2.24 × 104.