STRUCTURAL DIFFERENCES OF OVALBUMIN AND S-OVALBUMIN REVEALED BY DENATURING CONDITIONS

We found, by circular dichroism and Raman spectroscopy measurements. t hat the secondary structure of the native ovalbumin and of its heat-st able form, called S-ovalbumin, is a probe of the structural difference s between the two proteins. Small angle X-ray scattering and circular dichroism measurements performed on the two proteins under denaturing conditions, with different concentrations of guanidine hydrochloride, show the changes of the tertiary and secondary structure and a differe nt pathway in the unfolding process. These experimental data confirm t hat the conversion of native ovalbumin into S-ovalbumin is irreversibl e and reveal that the response of the two proteins to the same chemica l environment is different.