Chemistry of the Caseins

Swaisgood, Harold E.

doi:10.1007/978-1-4419-8602-3_3

Cited by 273 publications

(333 citation statements)

References 236 publications

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“…Unlike the calcium-sensitive caseins, k-cas is poorly phosphorylated. Instead, this casein is known to be O-glycosylated on multiple sites (for review see Swaisgood, 2003). Hence, one can speculate that the multiplicity of the k-cas spots could reflect different levels of glycosylation of the molecule, each form containing different amounts of sialic acid and thus bearing distinct charges.…”

Section: Resultsmentioning

confidence: 99%

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Lipid-deprived diet perturbs O-glycosylation of secretory proteins in rat mammary epithelial cells

Lavialle¹,

Chanat²

2008

Animal

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Nutrition modulates both production and composition of milk. Milk composition was studied in rats chronically fed a diet without additional lipids, and therefore eating only traces of the recommended supply of essential polyunsaturated fatty acid. Despite a large decrease in milk-protein synthesis, only protein composition, but not protein concentration, was found to change in the milk of rats following a lipid-deprived diet. Correlatively, we observed a substantial increase in the lactose concentration of milk. Analysis of milk proteins by two-dimensional electrophoresis demonstrated that the relative proportion of the various molecular forms of k-casein, an O-glycosylated protein, was modified in the milk of rats receiving the lipiddeprived diet. In tissues, differences in the two-dimensional pattern of k-casein between control and lipid-deprived rats were similar, if not identical. In contrast to k-casein, the molecular forms of a-lactalbumin, an N-glycosylated protein, were not affected by the diet. These data provide evidence that O-glycosylation of milk proteins in the secretory pathway of mammary epithelial cells is modulated by the lipid content of experimental diets.

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Section: Resultsmentioning

confidence: 99%

“…Caseins (cas), a family of acidic phosphoproteins (a s1 -cas, a s2 -cas, b-cas and k-cas), are the most abundant proteins in milk, except in primates (for review see Swaisgood, 2003). k-cas is O-glycosylated and forms dimers via highly conserved cysteine residues (Bouguyon et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Lipid-deprived diet perturbs O-glycosylation of secretory proteins in rat mammary epithelial cells

Lavialle¹,

Chanat²

2008

Animal

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“…Table 1 also indicates the presence of a carbohydrate group (group 6) in the model. The glycoprotein -casein is known to contain three or four carbohydrate moieties, attached to its threonyl and the single serine residues between positions 131 to 142 (Swaisgood, 2003). The moieties are each made up of three or four sugar groups (see Fig.…”

Section: Models For -Casein and Para--caseinmentioning

confidence: 99%

“…It is also a glycoprotein, with around three or four short glycosidic chains, each consisting typically of 3 or 4 sugar moieties attached to threonyl residues in positions 131,133,135 and 142, and serine one in position 141, counted along the protein backbone from its N-terminus (Swaisgood, 2003). During renneting processes, the enzyme chymosin hydrolyses the bonds between phenylalanine and methionine residues (105-106) to split the -casein into two separate chains.…”

Section: Introductionmentioning

confidence: 99%

Interactions between casein layers adsorbed on hydrophobic surfaces from self consistent field theory: κ-casein versus para-κ-casein

2014

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Interactions mediated by layers of -casein and para--casein have been calculated and compared using the self consistent field (SCF) approach, at pH and electrolyte concentrations found in milk. Our results show the interaction potentials at close separation distances to be repulsive for -casein, while they are attractive for para--casein. We have also studied -casein chains stripped of their sugar moieties and highlighted the important role that the carbohydrate side chains play in the provision of steric forces. The point of transition from a repulsive to an attractive interaction is found to be rather sensitive to the degree of coverage of the surface by the protein chains. At =0.0025 chains per unit monomer area, the value is just over 40%, whereas at =0.0032 this increases to 87%. At the coverage values higher than those we estimate for the surface of casein micelles, no transition is detected and the interactions remain repulsive even when all of -casein has been converted to para--casein, as already shown by Mellema, Leermakers, & de Kruif (1999). At lower surface coverage values, the interaction potential curves for otherwise uncharged surfaces, covered with para--casein, posses an energy barrier. We have demonstrated that the origin of this energy barrier is electrostatic, with para--casein contributing a net positive charge to the surface.We have also explored the importance of the asymmetry in the distribution of charge between the para--casein and the glycomacropeptide sides of the protein. The glycomacropeptide is net negative while para--casein side is net positive at neutral pH. Our results suggest that on a negatively charged surface, such as the surface of casein micelles, this uneven distribution of charge is just as important in determining the conformation of -casein chains as is the difference in the hydrophobic and hydrophilic nature of the two sides of this protein.

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“…κ-casein is an amphiphilic protein containing cysteine residues, which may participate in formation of intra-and/or intermolecular disulphide bonds. 29 When extracted from milk, κ-casein may be present as oligomers. 30 The thiol groups furthermore may interact with the surface of the sensor chip or be available for interactions with glucans.…”

Section: Ph Optimamentioning

confidence: 99%

Binding Interactions Between α-glucans from Lactobacillus reuteri and Milk Proteins Characterised by Surface Plasmon Resonance

et al. 2012

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Chemistry of the Caseins

Cited by 273 publications

References 236 publications

Lipid-deprived diet perturbs O-glycosylation of secretory proteins in rat mammary epithelial cells

Lipid-deprived diet perturbs O-glycosylation of secretory proteins in rat mammary epithelial cells

Interactions between casein layers adsorbed on hydrophobic surfaces from self consistent field theory: κ-casein versus para-κ-casein

Binding Interactions Between α-glucans from Lactobacillus reuteri and Milk Proteins Characterised by Surface Plasmon Resonance

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