A Raman difference spectroscopic investigation of ovalbumin and S‐ovalbumin

Raman spectra from 800 to 1850 cm −1 of aqueous solutions of ovalbumin and its more heat‐stable form, S‐ovalbumin, are presented. A Raman difference spectrum (ovalbumin minus S‐ovalbumin) shows differences in intensity in the amide I and III regions. These intensity differences lead us to postulate that the conversion of ovalbumin to S‐ovalbumin involves a conformation change of a small part (∼3–4%) of the protein from α‐helix to antiparallel β‐sheet geometry. This small difference in the three‐dimensional arrangement of the peptide chain may contribute to the large difference in the thermodynamic stability between ovalbumin and S‐ovalbumin.