Plastein, a product of protease-induced peptide aggregation is thought to be important due to, among other things, the potential of its modified peptide structure to contribute to health-promoting functions, including hypolipidaemic properties. In this study, papain-derived bovine serum albumin (BSA) hydrolysate and plastein solutions were studied at low sample concentrations (0.1%, w/v) in order to evaluate the properties of enzyme-induced peptide aggregation and role of posttranslational modifications during plastein formation. Data from this study confirms a role for hydrophobic and electrostatic interactions in peptide aggregation as supported by the decrease in turbidity (absorbance at 460 nm) of the BSA plastein in both a surfactant (SDS) and a high ionic strength (NaCl) solutions compared to aqueous environments. The evaluation of surface charge distribution also showed a significant reduction of zeta potential (from -31.6 mV to -10.8 mV) upon plastein formation, as well as increased particle size of the plastein (5510 nm) compared to that of the hydrolysate (79 nm). The changes in the surface structure are important in determining biomolecular interactions with plastein peptides. Shotgun-based peptidomics workflow revealed that 19% and 15% of peptides in the BSA hydrolysates and plastein, respectively, were modified by deamidation and pyroglutamylation. Thus, it is probable that the increased hydrophobicity associated with these peptide modifications did not play a significant role in peptide aggregation during plastein reaction. Taken together, the modified surface properties of plastein, such as its increased surface hydrophobicity, could be important factors in determining its binding affinity for hydrophobic biomolecules e.g. bile acids, and thus in its use for the design of food-based formulations for the management of conditions such as dyslipidaemia.

Role of plastein structure in biomolecular interactions of peptides

2019 Fall National Meeting

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