ANALYTICAL DESCRIPTION OF PROTEIN ELECTRON-VIBRATION SPECTRA

Electron-vibration phosphorescence and fluorescence spectra of tryptop han residues obtained at 77 degrees K are best described by two indepe ndent series of normal components. Each of them corresponds to one typ e of vibrations. Phosphorescence and fluorescence spectra of several p roteins with different localization of the tryptophan residue were app roximated by a curve plotted according to the model proposed. The resu lts obtained indicate that the tryptophan phosphorescence band describ es vibrations of two types with a frequency of 650-800 and 1350-1500 c m(-1). Replacement of H2O with D2O had no effect on the frequency of b oth vibrations in the phosphorescence spectra of human serum albumin, melittin, and tryptophan in 1 M KCl. Therefore, the 1350-1500 cm(-1) s eries is likely to correspond to the W5 vibration (B19(a) vibration of benzene ring). The 650-800 cm(-1) series describes W18 vibrations, i. e., breathing vibration of the indole ring. Some low-temperature fluor escence parameters were found to correlate with those of phosphorescen ce.