Spread and adsorbed layers of protein fibrils at water –air interface

The properties of adsorbed layers of protein fibrils differ significantly from the properties of fibril spread layers on an aqueous subphase. If the dependencies of the dynamic surface elasticity on surface pressure of Lysozyme (LYS) and β-lactoglobulin (BLG) aqueous dispersions proved to be close to the results for native protein solutions, LYS and BLG spread layers on the surface of 0.1 M NaCl solution exhibited the surface elasticity more than two times higher than the values for protein solutions with the same NaCl concentatration, presumably due to lower surface concentrations of hydrolysed peptides in the latter case. The properties of fibril spread and adsorbed layers and also their morphology, unlike the surface properties of protein solutions, depend noticeably on the ionic strength of the aqueous bulk phase. This dependence is stronger in case of LYS layers, which are also more prone to the formation of macroscopic and mesoscopic surface aggregates as compared with BLG layers. [Display omitted] •LYS and BLG spread layers exhibit surface elasticity two times higher than the values for protein solutions.•Admixtures of peptides of low molecular mass influence surface properties of fibril layers.•The compression of protein fibril layers results in monotonic compression isotherms.•Both spread and adsorbed LYS fibril layers have higher dynamic elasticity than BLG layers.•Lys is more prone to aggregation at the interface than BLG.