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. Author manuscript; available in PMC: 2008 Nov 20.
Published in final edited form as: Biochemistry. 2007 Oct 24;46(46):13254–13268. doi: 10.1021/bi7014986

Figure 4.

Figure 4

Spectroelectrochemistry and EPR spectroscopy of NP7–NO complexes. (A) UV-visible spectra of wt NP7–NO in 100 mM NaH2PO4/NaOH (pH 5.5) as a function of applied potential (−200, −180, −160, −140, −120, −100, −80, −60, −40, −20, and 0 mV vs. Ag/AgCl; add 205 mV for potential vs. SHE). Inset: Fit of the spectroelectrochemical data. (B) EPR spectrum of wt NP7II–NO in 50 mM NaOAc/HOAc (pH 5.0) recorded at 4.2 K at X-band. Other than a small amount of high-spin FeIII (g∥ = 5.95) originating from unligated NP7, the signal is characteristic of 5-coordinate FeII–NO heme centers (giso = 2.01; see Inset for detailed resolution) (58, 59). (C) UV-visible spectra of NP7(Δ1-3)–NO in 100 mM MOPS/NaOH (pH 7.5) as a function of applied potential (−140, −120, −100, −80, −60, −40, −20, 0, +20, +40, +60, +80, and 100 mV vs. Ag/AgCl; add 205 mV for potential vs. SHE). Inset: Fit of the spectroelectrochemical data.