Study of a murine IgG2a monoclonal antibody by vibrational spectroscopies

The Raman and FTIR spectra of a murine IgG2a monoclonal antibody molecule i n anhydrous state and in aqueous solutions of H2O and D2O are reported. The secondary structural characteristics have been investigated and have been established from absorption measurements in the amide I, I' and II, II' fre quency range. In an anhydrous state, in accordance with previous studies on immunoglobulins, the secondary structures is predominantly of the beta-she et type. Data obtained in different polar media (KBr, H2O, D2O) reveal that IgG2a is a highly flexible protein. In pure H2O and D2O a rapid solvation of free peptide units occurs.