Thermodynamics of Micellization of Bovine β-Casein Studied by High-Sensitivity Differential Scanning Calorimetry

Abstract

High-sensitivity differential scanning calorimetry was applied for the first time to study the micellization of bovine β-casein in aqueous solutions, complemented by analytical ultracentrifugation data. The micellization was described as a single endothermic heat capacity peak located in the temperature range of 0−50 °C. The transition originated at temperatures very close to 0 °C. The position of the heat capacity peak was strongly dependent on the protein concentration and the solvent composition. Thermodynamic parameters of the micellization, the transition temperature and enthalpy, were determined over a wide range of protein concentration. The observed thermal behavior of β-casein was well fitted by the thermodynamic shell model of micellization proposed by Kegeles (J. Phys. Chem. 1979, 83, 1728). The effects of different cosolutes (inorganic salts, urea, Tris, and ethanol) on the thermodynamic parameters of micellization of β-casein underline the hydrophobic character of the transition.

Enhancement of the aqueous solubility and permeability of a poorly water soluble drug ritonavir via lyophilized milk-based solid dispersions

“…Their structure consists of amphiphilic, di-block copolymers forming micellar aggregates which forms a microstructure and acts as a surfactant to assist drug solubilization. 26,[29][30][31] Milk also contains whey proteins with b-lactoglobulin, a-lactalbumin, bovine serum albumin and immunoglobulins as principle fractions. 32 These molecules are reported to be surface active with superior solubility than caseins.…”

Casein structures in the context of unfolded proteins

“…In the past, the self-association of individual caseins and the association of casein mixtures in the absence of calcium ions or calcium phosphate have been likened to that of detergent molecules in which the hydrophobic effect (Cramer & Truhlar, 1992;Kauzmann, 1959) is assumed to provide the driving force (Horne, Lucey, & Choi, 2007;Mikheeva, Grinberg, Grinberg, Khokhlov, & de Kruif, 2003;Payens & Vreeman, 1982). Comparison with similar unfolded proteins suggests that an alternative driving force is more likely which involves main-chain-to-main-chain interactions of low sequence specificity rather than the side-chain interactions of the hydrophobic effect.…”

Beta casein-micelle as a nano vehicle for solubility enhancement of curcumin; food industry application

“…B-CN is an amphiphilic self-assembling protein, which forms small oblate micelles (as demonstrated by cryo-electron microscopy and dynamic light scattering studies) with a diameter of approximately 13 nm in aqueous solutions. Their structure reminds amphiphilic diblock copolymers forming micellar aggregates (Dauphas et al, 2005;Mikheeva, Grinberg, Grinberg, Khokhlov, & de Kruif, 2003;Portnaya et al, 2008). Camel B-CN (accession number Q9TVD0) has 217 amino acids and a pI of 5.7.…”