Phosphorylation and glycosylation of caseins

Engineering artificial casein micelles for future food: Preparation rate and coagulation properties (2024) https://www.sciencedirect.com/science/article/pii/S0260877423004661

• Artificial casein micelles were similar in structure to bovine casein micelles.
• Their coagulation behaviour and curd grain functionality were comparable.
• The size of artificial casein micelles depended on the preparation rate.
• Speeding up the current process impaired the coagulation behaviour.
• The characteristic time of casein micelle self-assembly is approximately 18 min.

Effect of composition, casein genetic variants and glycosylation degree on bovine milk whipping properties (2024)

• Bovine ĸ- and β-casein genetic variants did not affect whipping properties.
• A lower degree of κ-casein glycosylation resulted in superior whipping properties.
• Larger casein micelle size resulted in superior whipping properties.

Engineering artificial casein micelles for future food: Is casein phosphorylation necessary? (2023) https://www.sciencedirect.com/science/article/pii/S0963996923008608

• Bovine casein was 89.2% dephosphorylated with alkaline phosphatase.
• Artificial casein micelles were prepared from dephosphorylated and native casein.
• Dephosphorylated casein stabilized calcium phosphate nanoclusters.
• Furthermore, it impaired and disrupted curd formation upon renneting.
• Casein phosphorylation is crucial for micelle formation.

The effect of casein genetic variants, glycosylation and phosphorylation on bovine milk protein structure, technological properties, nutrition and product manufacture (2022) https://www.sciencedirect.com/science/article/pii/S0958694622001248

• Whilst phosphorylation is found in all casein types, glycosylation occurs only in κ-CN (Bonfatti, Chiarot, & Carnier, 2014) and it is estimated that 60% of κ-CN is glycosylated, while 40% remain unglycosylated (Holland & Boland, 2014).
• negative relationship between casein micelle size and the proportion of κ-CN to total casein is believed to influence casein micelle dynamics (Poulsen, Glantz, Rosengaard, Paulsson, & Larsen, 2017), and relate to the κ-CN glycosylation level, with a strong negative correlation for milk with glycosylated κ-CN but not unglycosylated κ-CN (Bijl et al., 2014b).
• κ-CN content has been shown to have a relationship with CN micelle structure and size and it is a well-established that milk with smaller native casein micelles exhibits enhanced gelation properties and results in the formation of firmer curds (Di Gregorio et al., 2017; Johnson et al., 2007; Khastayeva et al., 2021; Čítek et al., 2021).
• Milk containing the dominant phosphorylated form (8P) of αS1-CN has been shown to correlate with faster chymosin-induced hydrolysis and better milk coagulation properties compared to more highly phosphorylated αS1-CN milk (e.g., 9P) (Bijl et al., 2014c; Jensen et al., 2012b). In addition to phosphorylation, glycosylation of κ-CN is correlated with milk coagulation properties. For example, the κ-CN B variant demonstrates better coagulation properties compared to κ-CN A (Bonfatti et al., 2014; Jensen et al., 2012b), with K-CN B exhibiting a higher degree of glycosylation (Coolbear et al., 1996).

Casein polymorphism heterogeneity influences casein micelle size in milk of individual cows (2015) https://www.sciencedirect.com/science/article/pii/S0022030215002167

• although the amount of κ-casein (both glycosylated and nonglycosylated) is associated with micelle size, an increased proportion of glycosylated κ-casein could be a more important and favorable factor for small micelle size.

Effects of milk proteins and posttranslational modifications on noncoagulating milk from Swedish Red dairy cattle (2020) https://www.sciencedirect.com/science/article/pii/S0022030220304549

• Noncoagulating milk significantly correlated with higher relative concentrations of α-lactalbumin and β-casein and lower relative concentrations of β-lactoglobulin and κ-casein. Regarding PTM of caseins, an effect on NC milk from a lower relative concentration of αS1-casein with 8 phosphate groups were found, even though an effect from total relative concentration of αS1-casein was not found.

Effects of genetic variants and sialylation on in vitro digestibility of purified κ-casein (2022) https://www.sciencedirect.com/science/article/pii/S0022030222000777

• low glycosylation degree of purified κ-CN promotes faster in vitro digestion rates, and that desialylation of the O-linked oligosaccharides further promotes digestion

The least number of phosphate groups for crosslinking of casein by colloidal calcium phosphate (1992) https://doi.org/10.3168/jds.S0022-0302(92)77838-2

• The casein aggregates crosslinked by colloidal calcium phosphate were formed in artificial casein micelles of the 3-P and 4-P components. In contrast, no cross-linkage was formed in artificial micelles of the 1-P and 2-P components. The results indicate that at least three phosphate groups are needed for crosslinking of casein by colloidal calcium phosphate.

Milk protein genetic variants and isoforms identified in bovine milk representing extremes in coagulation properties (2012) https://www.sciencedirect.com/science/article/pii/S0022030212002652

• In milk with good coagulation ability, a high prevalence of the B variants of all 3 analyzed proteins were identified, whereas poorly coagulating milk was associated with the β-CN variant A2, κ-CN variant A or E, and β-LG variant A or C.
• around 95% of total κ-CN was phosphorylated with 1 or 2 phosphates attached, whereas approximately 35% of the identified κ-CN was glycosylated with 1 to 3 tetrasaccharides

Post-translational modifications of caseins (2008) https://www.sciencedirect.com/science/article/abs/pii/B9780123740397000040?via%3Dihub

• Phosphorylation of the α- and β-caseins and glycosylation of κ-casein are the best-known modifications and are critical for the formation and stability of casein micelles.