LASER RAMAN-SPECTRA OF GLUCAGON

Laser Raman spectroscopy study indicates that in concentrated fresh acidic solution (30 mg/ml), glucagon remains predominantly α-helix and not random-coil. The splitting of the amide III band into three components in the crystal at 1262, 1275, and 1295 cm-1 is due to the α-conformation as expected. The presence of a small fraction of β-conformation is demonstrated by the appearance of the weak band at 1230 cm-1 in the fresh solution. This study also established the frequencies of amide III′ bands for the α- and β-conformations of glucagon: 957 and 988 cm-1 for α and β forms, respectively. The conformations of acidic and basic glucagon solutions are apparently different. © 1979.