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. Author manuscript; available in PMC: 2023 Feb 2.
Published in final edited form as: J Am Chem Soc. 2022 Jan 18;144(4):1534–1538. doi: 10.1021/jacs.1c12506

Figure 4.

Figure 4.

EPR spectroscopic characterization of CrHydA1 maturated with [2]2−. X-band continuous-wave (CW) EPR spectra (15 K) of (A) [2]2−-CrHydA1 and (E) 13CN-[2]2−-CrHydA1 oxidized by thionine. Both spectra are simulated using two components: Hox in red with g = [2.103, 2.041, 1.998] and Hox-CO in gray with g = [2.055, 2.009, 2.007]. (B) Q-band 13C- and (C) 15N-Mims ENDOR spectra of [2]2−-CrHydA1 with the isotopically labeled 15NH(13CH2)2 bridgehead as illustrated in (D). (F) Q-band 13C-Davies ENDOR spectra of 13CN-[2]2−-CrHydA1, as illustrated in (G). The ENDOR spectra were recorded at 15 K and at the magnetic field positions corresponding to g1 = 2.103 and g3 = 1.998 of Hox, where there are no EPR signal contributions from Hox-CO. The black traces are experimental spectra, and the colored traces are simulated spectra (details in the Supporting Information). The ENDOR features marked by asterisks in (C) correspond to the third-order harmonics of 13C ENDOR signals shown in (B).