SIMULTANEOUS DIFFERENTIAL SCANNING CALORIMETRY, X-RAY-DIFFRACTION ANDFTIR SPECTROMETRY IN STUDIES OF OVALBUMIN DENATURATION

The new application of differential scanning calorimetry (DSC) and the susceptibility of ovalbumin to cc-chymotrypsin gave a quantitative es timation of protein denaturation in solid ovalbumin. Solid ovalbumin i n granules with 11% of water was heated at 100 degrees C in closed and nonclosed ampules. In order to compare effects of size and crystal st ructure, two proteins (bovine albumin and gamma-globulin) were examine d at similar conditions for the extent of denaturation. Ovalbumin and bovine albumin showed similar extents of denaturation, but gamma-globu lin, with a very different molecular mass, showed the maximal conforma tional changes. The enthalpy of denaturation was measured to elucidate the conformational changes in solid proteins. Its value was used for calculation of the degree of denaturation. The thermodynamic data asso ciated with transition were calculated and the number of bonds broken during denaturation was determined. Intrinsic fluorescence was utilize d in order to compare these two methods. Moreover, X-ray diffraction a nd FTIR spectrometry were applied to native and denatured proteins. (C ) Munksgaard 1995.