Figure 2.

Room-temperature Raman spectra recorded from the aqueous samples of cFEE. The spectra obtained at (A) pH 3 and (B) pH 7. The tentative assignment of the main Raman bands is made on the basis of the data corresponding to free AAs (Figure 3). Amide (I and III) and disulfide bond regions are noted. See Figures 4 and 5 for band decomposition of these particular regions. The characteristic Raman bands sensitive to the Glu side-chain protonation/deprotonation are marked by pink arrows. Phe and bk designate the Raman bands assigned to phenylalanine residue and backbone, respectively.