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. Author manuscript; available in PMC: 2012 May 10.
Published in final edited form as: J Am Chem Soc. 2011 Apr 14;133(18):6968–6977. doi: 10.1021/ja107052p

Figure 5.

Figure 5

EPR spectra for EAL ternary complex, holo-EAL, and difference spectrum for ternary complex minus holo-EAL, following long-term photolysis, and control EPR spectrum of the (S)-2-amino-2-propanol-generated cob(II)alamin-substrate radical pair generated by the native, thermal reaction. Note that the ordinate scale in (A)-(C) is expanded by a factor of 80, relative to the scale for (D). (A) Holo-EAL. (B) EAL ternary complex. (C) Difference EPR spectrum; ternary complex (B) minus holo-EAL (A). (D) Cob(II)alamin-substrate radical pair EPR spectrum, following 15 min incubation at 275 K (EAL active site concentration, 150 μM; AdoCbl, 300 μM; (S)-2-amino-1-propanol, 10 mM). Photolysis conditions: EAL active sites, 120 μM; AdoCbl, 60 μM. Iirradiation for 1.5 min with the 532 nm output of the pulsed Nd-YAG laser (10 Hz, 50 mJ/pulse) at 230 K. EPR conditions: Temperarure, 120 K; microwave frequency, 9.436 GHz; microwave power, 20 mW; magnetic field modulation, 10 Gauss peak-peak; modulation frequency, 100 kHz; field sweep rate, 1.5 Gauss s−1; time constant, 200 ms; average of 2 sweeps, minus average of 2 baseline spectra.