FIG. 2.

(a) Steady-state Fe K-edge absorption spectra of MbNO and (unligated) deoxy-Mb. (b) Transient spectrum (excited minus unexcited sample X-ray absorption) recorded 70 ps after excitation of the sample at 532 nm (o; with error bars). The difference of the deoxy-Mb minus MbNO (called the static difference spectrum) steady-state X-ray absorption spectra (a) is shown in red. The deviations around 7.135 keV and 7.165 keV between the two traces are due to the formation of a domed ligated heme. Reproduced with permission from Silatani et al., Proc. Natl. Acad. Sci. U.S.A. 112, 12922 (2015). Copyright 2015 National Academy of Sciences.