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 differ ence-spectrum and self-deconvolution have been used to follow the cour se of thermally-induced changes in the amide-I (1700-1600 cm(-1)) spec tral regions. The 1653 cm(-1) band which is assignable to the alpha-he lix structure rapidly loses its intensity above 90 degrees C, whereas a new 1628 cm(-1) band which is assignable to the extended chain struc ture appears. The intensity at 1628 cm(-1) increases between 90 degree s C and 120 degrees C and decreases between 120 degrees C and 200 degr ees C. These results indicate that the alpha-helix of myoglobin is tra nsformed into the extended chain at 90 degrees C and then transformed into the other unordered form at 120 degrees C.