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. Author manuscript; available in PMC: 2013 Oct 9.
Published in final edited form as: Biochemistry. 2012 Sep 25;51(40):7891–7900. doi: 10.1021/bi3006708

Figure 7.

Figure 7

35 GHz EPR and ENDOR spectra. (A) Absorption-display CW Q-band EPR spectra of tagged WT-sCoaT, C327A-sCoaT and WT-sCoaT at 2K. Each sample exhibits a S = 3/2 Co2+ signal as characterized from the broad feature at g⊥ = 3.9. Adventitious Cu2+ in variable amounts is observed at higher fields, but no copper is detectable in the samples by ICP-OES. (B) 14N Davies ENDOR spectra taken near g⊥. Goalpost centered at A′/2, split by 2 × ν(14N). (C) 1H CW ENDOR spectra of WT-CoaT in 1H2O (solid line) and 2H2O buffer (dashed line) taken near g⊥. Shading highlights intensity from exchangeable proton. Goalpost centered at ν(1H), split by A′. CW EPR and ENDOR conditions: microwave frequency, 34.9 GHz; modulation amplitude, 2 G; time constant, 32 ms; EPR scan time, 4 min; ENDOR scan rate, 2 MHz/sec. Pulse ENDOR conditions: microwave frequency, 34.6 GHz; π, 80 ns; τ, 600 ns; TRF, 30 μs; repetition rate, 20 ms.