THERMALLY-INDUCED CONFORMATIONAL-CHANGES IN SOLID-STATE PROTEIN MONITORED BY FT-IR

Heat denaturation of the secondary structure of sperm whale myoglobin has been studied in the solid state by FT-IR. The techniques of difference-spectrum and self-deconvolution have been used to follow the course of thermally-induced changes in the amide-I (1700-1600 cm(-1)) spectral regions. The 1653 cm(-1) band which is assignable to the alpha-helix structure rapidly loses its intensity above 90 degrees C, whereas a new 1628 cm(-1) band which is assignable to the extended chain structure appears. The intensity at 1628 cm(-1) increases between 90 degrees C and 120 degrees C and decreases between 120 degrees C and 200 degrees C. These results indicate that the alpha-helix of myoglobin is transformed into the extended chain at 90 degrees C and then transformed into the other unordered form at 120 degrees C.