Fig. 2.
NRVS spectra of 57Fe(III) Ht Cyt c (A) and 13C8-heme–labeled (B), 13C15N-Met–labeled (C), and 13C15N-pp–labeled (D) protein in 50 mM Hepes buffer containing 10% (vol/vol) glycerol (pH 7.0, 16.5–18 mM). K2IrCl6 was added to a concentration of 25 mM to prevent sample reduction. VDOS, vibrational density of states.