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. Author manuscript; available in PMC: 2019 Jul 1.
Published in final edited form as: J Inorg Biochem. 2018 Mar 26;184:146–155. doi: 10.1016/j.jinorgbio.2018.03.012

Figure 1.

Figure 1

The scheme of an LFP experiment showing all relevant kinetic rate constants and using iNOS oxyFMN construct as an example. The ready (R) state, [FMNH•][Fe(II)–CO], is prepared from the initial [FMN][Fe(III)] state by a continuous illumination of CO-containing NOS solution with white light for 2 – 4 minutes. The sample in the R-state is then illuminated by a laser flash at 446 nm, which results in dissociation of CO ligand from the ferrous heme center(s). The resulting [FMNH•][Fe(II)] state is an active (A) state in terms of the forward heme → FMN IET. Such an IET converts the enzyme to the final (F) [FMNhq][Fe(III)] state, from which the backward FMN → heme IET converting the system back to the A-state is possible. The solution CO molecules can rebind to the ferrous heme center(s) in the A-state, which gradually returns the system back to the R-state. The CaM-binding tether and the outlines of the FMN domain and CaM corresponding to the undocked state are shown by dashed lines, while those corresponding to the docked state are shown by solid lines.