Characterization of protease activities in a crude extract of germinated cacao

Dynamic light scattering (DLS) was applied to the analysis of the hydrodynamic diameter distribution of proteins in extract of germinated cacao. The interactions among divalent cations and their relation with the activity of Xaa-prolyl dipeptidyl aminopeptidase 2 (Xaa-Pro-DAP2) enzyme were evaluated. The peptidases were isolated by 80% saturation of ammonium sulfate from acetone extract of germinated cacao seeds. The results showed a higher activity of Xaa-Pro-DAP2, besides aminopeptidase (APE) and carboxypeptidase (CP) enzymes. Using DLS analysis the size distribution was found to be multi-modal; however with Cu²⁺ and Cd²⁺ at 1 mM, the size distribution was found to be monomodal with a hydrodynamic diameter of 158.5 and 119 nm, respectively. The distribution remained constant from 60 to 80°C, suggesting that thermal stability is related to increase in Xaa-Pro-DAP2 activity an lower protein aggregation. APE activity was slightly activated by Co²⁺ at 1 mM, whereas no significant effect was observed on CP activity.