Differential scanning calorimetry of a conformational transition in heavy meromyosin

Simultaneous differential scanning calorimetry, X-ray diffraction and FTIR spectrometry in studies of ovalbumin denaturation

The new application of differential scanning calorimetry (DSC) and the susceptibility of ovalbumin to alpha-chymotrypsin gave a quantitative estimation of protein denaturation in solid ovalbumin. Solid ovalbumin in 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 structure, two proteins (bovine albumin and gamma-globulin) were examined at similar conditions for the extent of denaturation. Ovalbumin and bovine albumin showed similar extents of denaturation, but gamma-globulin, with a very different molecular mass, showed the maximal conformational 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 associated with transition were calculated and the number of bonds broken during denaturation was determined. Intrinsic fluorescence was utilized in order to compare these two methods. Moreover, X-ray diffraction and FTIR spectrometry were applied to native and denatured proteins.

Protein adsorption on low-temperature isotropic carbon: I. Protein conformational change probed by differential scanning calorimetry

This is the first of a set of articles on protein adsorption on low-temperature isotropic carbon (LTIC), a reputed blood compatible material. Surface-induced conformational changes of albumin, fibrinogen, and some small proteins were measured by differential scanning calorimetry (DSC) on LTIC powders and colloidal silica. The LTIC surface significantly alters the DSC response (denaturation?) in proteins studied in different buffer solutions. We use the term "denaturation" to refer to altered protein behavior in the adsorbed state. Hydrophobic interactions between LTIC and the proteins are thought to be the major driving force. The presence of air at the water-carbon interface seems to prevent the surface denaturation of fibrinogen. The silica surface greatly denatures albumin but only slightly denatures fibrinogen. Because LTIC is considered to be a nonthrombogenic material, but silica is considered to be a thrombogenic one, whether a surface denatures adsorbed proteins cannot be the sole criterion for its blood compatibility. The latter largely depends on what protein the surface denatures, and in what sequences.