Figure 1.

(A) FTIR absorbance spectra of apoMb in D₂O (²H₂O) (4.2 mg/ml in 0.01 M NaCl, uncorrected pH = 5.3) in the region of the amide I band, as a function of temperature from 32° to 55°C. The temperature-dependent D₂O background has been subtracted from each FTIR spectrum. (B) Second-derivative spectrum at 40°C; major components of amide I are observed at 1675, 1650, and 1633 cm⁻¹. (C) Difference spectra, generated by subtracting the spectrum at 32.8°C from the spectrum at each temperature. The primary difference peaks occur at 1673 and 1648 cm⁻¹.