Adsorption kinetics of ovalbumin monolayers

Unexpected differences in the behavior of ovotransferrin at the air–water interface at pH 6.5 and 8.0

“…This phenomenon, known as the ''image charge effect'', is attributed to a barrier effect at the first stages of adsorption, when the chemical potential of the protein at the air-water interface is equal or greater than that of the protein in the bulk [47,66]. The influence of electrostatic interactions was already described [67] in the 1970s where the effects of electrostatic repulsion existing between charged proteins give rise to an initial desorption of proteins which accumulate into the sub-surface. Consequently, there are some modifications of the thermodynamical conditions which produce conformational changes and the migration of proteins to the interface.…”

Interfacial properties of fractal and spherical whey protein aggregates

“…Studies on the effect of protein net charges were based on the kinetic of increase of surface pressure and adsorbed amount for protein solutions at different pH values. [16][17][18][19] In these studies, the rate of adsorption and the total adsorbed amount have been found to be highest at pH values close to the isoelectric point where the proteins carry no net charge. Nevertheless, since changing the pH also induces changes in the tertiary and quaternary structures of globular proteins, the pH range that can be investigated to study charge effects on interfacial behavior is limited.…”

“…[20][21][22] The alternative approaches were then to chemically modify the net charge of globular proteins 23,24 or to screen the electrostatic charges by increasing the ionic strength. [16][17][18][19]23,25 Thus, the protein net charge remains constant while the repulsion energy is lowered, which reduces the contribution from the electrostatic forces to the surface pressure. Increasing the ionic strength was found to result in an increase in the rate of adsorption, the steady-state adsorbed amount and the surface pressure.…”

Effect of surface charge on adsorption of bovine serum albumin 2. Interaction of protein molecules with an anionic monolayer, as studied by ellipsometry, radiotracer and surface tension measurements

“…It appears that the equilibrium surface pressures for the monolayer/solution interface are likely to approach those equilibrium values observed for the air/solution interface where the surface is thoroughly covered with the denatured BSA. The continuous rise of the curves observed for the air/water interface may indicate that surface denaturation or rearrangement of adsorbed BSA is occurring, as have often been reported by many workers [18,19].…”