Influence of succinylation on the conformation of yak casein micelles

Influence of succinylation on physicochemical property of yak casein micelles

“…Chemical modification of yak casein micelles followed the method of Yang, Cui, Fang, Shi, Yang and Wang (2015). Dried caseins were dissolved in distilled water at 20 mg/mL by constant mixing at 3,000 rpm (40°C).…”

“…Surface hydrophobicity decreased (p < 0.05) with increasing succinylation level. Even though succinylation induced substantial changes in the spatial structures of yak casein micelles (e.g., loose casein micelles structures, resulting in the exposure of more tryptophan residues to the polar environment), both steric hindrance and electrostatic repulsion prevented the negatively charged hydrophobic ANS probe from approaching and binding to the hydrophobic sites in the succinylated caseins (Knopfe, Schwenke, Mothes, Mikheeva, Grinberg, Görnitz, et al, 1998;Yang, et al, 2015). Paulson and Tung (1987) reported that increasing succinylation levels contributed to an increase in charge frequency and electronegativity and to a decrease in surface hydrophobicity of proteins.…”

“…Succinylation leads to the link of hydrophilic carboxy group on the surface of the casein micelles (Yang, et al, 2015). Furthermore, the association between the bulky, negatively charged succinyl groups and the lysine residues of caseins induced electrostatic repulsions and steric hindrance, resulting in the looser structure than native yak casein micelles.…”

“…At the highest succinylation level, ∆H increased sharply, with a value higher than that of native caseins. The structure of the sub-micelles may remain intact at 82% level of succinylation, and sub-micelles had more regular structures (Yang, et al, 2015). Furthermore, a large number of hydrogen bonds could be formed among sub-micelles or intra-and intermolecular of caseins with 82% succinylation, contributing to high ∆H values.…”

Succinylation Improves the Thermal Stability of Egg White Proteins

“…The result of differential calorimetry scanning illustrated that the stability of milk protein decreased, while the introduction of the succinic group increased the surface hydrophobicity and changed the surface charge state, which, in turn, suppressed the aggregation of protein [13,14]. Succinylation promoted the dissociation of phosphoprotein of yak casein micelles and changed the secondary structure of protein, thus lowering the surface hydrophobicity and heat stability of yak casein micelles [15,16]. Oat protein and soy protein are similar to other proteins, and succinylation can alter the secondary and tertiary structure of protein, which improves the colloid stability and suppresses the aggregation of protein while decreasing the thermal stability of protein [17,18].…”