Bovine Serum Albumin Unfolding at the Air/Water Interface as Studied by Dilational Surface Rheology

Abstract

Measurements of the surface dilational elasticity close to equilibrium did not indicate significant distinctions in the surface conformation of different forms of bovine serum albumin (BSA) in a broad pH range. At the same time, the protein denaturation in the surface layer under the influence of guanidine hydrochloride led to strong changes in the kinetic dependencies of the dynamic surface elasticity if the denaturant concentration exceeded a critical value. It was shown that the BSA unfolding at the solution surface occurred at lower denaturant concentrations than in the bulk phase. In the former case, the unfolding resulted in the formation of loops and tails at surface pressures above 12 mN/m. The maximal values of the dynamic surface elasticity almost coincided with the corresponding data for the recently investigated solutions of β-lactoglobulin, thereby indicating a similar unfolding mechanism.

Temperature is key to yield and stability of BSA stabilized microbubbles

“…At ionic strength of 0.4 M and higher Dibbern, Toublan, and Suslick (2006) observed a decrease in microbubble yield. It has been described in literature (Noskov, Mikhailovskaya, Lin, Loglio, & Miller, 2010;Pereira, Theodoly, Blanch, & Radke, 2003) that a high surface coverage and a more rigid airewater interface at pH close the isoelectric point, or upon salt addition, can be attributed to both the charge and the conformation of the molecules. A decreased repulsion between molecules appears to result in a higher coverage at the airewater interface (Pereira et al, 2003).…”

“…A decreased repulsion between molecules appears to result in a higher coverage at the airewater interface (Pereira et al, 2003). Furthermore, at pH around the isoelectric point and at high ionic strength BSA molecules are in a native, more compact conformation, allowing a more efficient filling of the available space (Noskov et al, 2010). This causes that during the first stage of sonication more bubbles are formed, with a coverage that is larger than the critical coverage to prevent coalescence at pH around the isoelectric point and at high ionic strength.…”

Adsorption of Bovine Serum Albumin (BSA) at the Oil/Water Interface: A Neutron Reflection Study

“…26 In fact, the secondary structure is lost only when a relatively high concentration of denaturants is added to the solution. 27 BSA molecules adsorb with the major axis parallel to the water surface, forming a relatively compact monolayer. 28 Not even with increasing protein concentration do the molecules in the primary monolayer lose their structure, but a secondary, diffuse layer forms underneath it, extending toward the aqueous phase.…”

Impact of hydroxypropylmethylcellulose on whey protein concentrate spread film at the air–water interface: Structural and surface dilatational characteristics

“…The main WPC components, ␤-lg, ␣-lac and BSA, would contribute to this structural transition. As these proteins being the principal in mass presents CR values ranged between 10 and 12 mN/m [31,34,35]. At higher pressure values, the film experimented the next structural transition: the film collapse, when the protein molecules structure form multilayers, which correspond to an arrangement without an apparent organization [36,37].…”