FIGURE 1.

(A) Electronic absorption spectra of ferric horse heart Mb (HHMb), mini Mb at pH 7.0 in 100 mM phosphate, and Mb/imidazole complex ([Imidazole] = 0.18 M) in 0.1 M Tris, pH 8.4. The 450–700-nm region has been expanded by a factor of eight. (B) Corresponding RR spectra in the low- and high-frequency regions using 413.1-nm excitation wavelength. Experimental conditions: HHMb, 1 s/0.5 cm⁻¹ and 2 s/0.5 cm⁻¹ accumulation time for the high- and low-frequency regions, respectively; 15-mW laser power at the sample; mini Mb, 900 s accumulation time, 12-mW laser power at the sample; Mb-Imidazole, 2 s/0.5 cm⁻¹ accumulation time and 20-mW laser power at the sample. The relative intensities of the RR bands are normalized on the ν₄ band (not shown). The low-frequency region has been expanded by 40%.