Figure 1.

Absorption characteristics of cytochrome bd in the Soret band. (A) Static absorption spectra of cytochrome bd: (a) fully reduced; (b) CO complex of the fully reduced state; (c) as-prepared oxygenated state; (d) CO complex of the MV state. (B) Evolution of spectral changes induced by femtosecond excitation of the fully reduced cytochrome bd at 590 nm. The difference spectra have been recorded versus the static R state at the indicated time intervals after the photoexcitation. (C) Spectra of the subpicosecond component (0.45–0.9 ps for different states) of the photobleaching induced in various states of cytochrome bd. Experiments have been carried out in the indicated redox and ligand binding states at λ_exc indicated in brackets. Solid line overlaying spectrum b: approximation with a single Gaussian. (D) γ-Absorption band of ferrous heme b₅₉₅ resolved by photobleaching of the R state with 590-nm excitation (crosses, redrawn from C, curve b) has been approximated by a single Gaussian (solid line a).