Comparative studies on thermodynamic characteristics of pea legumin and legumin-T thermal denaturation

Characteristics of thermal denaturation of pea legumin and a product of its limited proteolysis with trypsin - legumin-T, in a wide range of NaCl concentrations have bean measured by means of differential scanning microcalorimetry. By the increase of NaCl concentration, the number of cooperative units (domains) increases from 1 per one polypeptide chain to 2 for legumin and 1.8 for legumin-T. Deconvolution of denaturation peaks have revealed up to three peaks, which were ascribed to the dissociation of protein macromolecules to subunits and the unfolding of alpha- and beta-polypeptide chains. The analysis of experimental data based on some assumptions showed that the splitting of C-termini of alpha-chains, which are not constituents of cooperative domains, in the course of limited trypsinolysis results in destabilization of the quaternary structure of legumin and loosening of alpha-chains, as well as decrease of the temperatures of their maximum stability.