Thermal Denaturation of Pea Globulins (Pisum sativum L.)-Molecular Interactions Leading to Heat-Induced Protein Aggregation

The heat-induced denaturation and aggregation of mixed pea globulins (8%, w/w) were investigated using differential scanning calorimetry (DSC), SDS-PAGE, and size-exclusion chromatography (SEC-HPLC). DSC data showed that the pea proteins denaturation temperature (T-d) was heating-rate dependent. The T-d value decreased by about 4 degrees C by lowering the heating rate from 10 to 5 degrees C/min. The SDS-PAGE analysis revealed that protein denaturation upon heating at 90 degrees C was mainly governed by noncovalent interaction. The SEC-HPLC measurements indicated that low-denatured legumin (approximate to 350-410 kDa) and vicilin/convicilin (approximate to 170 kDa) globulins were heat-denatured and most of their subunits reassociated into high-molecular weight, soluble aggregates (>700 kDa). The addition of N-ethylmaleimide slightly modified the aggregation route of pea globulins. However, partially insoluble macroaggregates were produced in the presence of dithiothreitol, reflecting the stabilizing effect of disulfide bonds within legumin subunits.