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Unité mixte de recherche "Science & technologie du lait & de l'œuf"

Unité mixte de recherche "Science & technologie du lait & de l'œuf"

Why some proteins are digested more slowly than others

Protein 3D
Caseins, the major milk proteins, are digested more slowly than other milk proteins, especially soluble proteins. This resistance to digestion induces subsequent metabolic outcomes.

Casein undergoes many post-translational modifications, eg. glycosylation and phosphorylation, which could account for its resistance to digestion. To verify this hypothesis, the glycosylated or unglycosylated caseinomacropeptide and the phosphorylated or unphosphorylated ß-casein (1-25) peptide were digested by intestinal enzymes of the brush border membrane vesicles.  

The kinetics and identification of peptides released throughout digestion show:

  • unglycosylated caseinomacropeptide and unphosphorylated peptide are more quickly digested than forms having post-translational modifications
  • both the glycosylation core and the number of the glycosylated chain modified the kinetics; the most heavily glycosylated forms being the slowest digested
  • both glycosylations and phosphorylations limited the action of endopeptidases.
Cinétique de digestion

 

Digestion kinetics are two times higher for the unphosphorylated ß-casein peptide (open symbol)
than for the phosphorylated (black symbol).

 

The post-translational modifications are implicated in the resistance of casein to digestion.
This resistance may be correlated to dietary allergy.

 

 

Read more 

Boutrou R., Coirre E., Jardin J., Léonil J.. (2010). Phosphorylation and coordination link of mineral inhibit the hydrolysis of the ß-casein (1-25) peptide by intestinal brush-border membrane enzymes, Journal of Agricultural and Food Chemistry 58: 7955-7961.

htpp://dx.doi.org/10.1021/jf100568r 

Boutrou R., Jardin J.,. Blais A., Tomé D., and Léonil J. (2008). Glycosylations of k-casein-derived caseinomacropeptide reduce its accessibility to endo- but not exo- intestinal brush border membrane peptidases, Journal of Agricultural and Food Chemistry, 56: 8166-8173.
http://dx.doi.org/10.1021/jf801140d

Contact

Rachel Boutrou: Rachel.Boutrou@rennes.inra.fr

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Writing: STLO
Creation date: 17 Janvier 2012
Update: 22 Octobre 2013