title: Stability of milk fat globule membrane proteins toward human enzymatic gastrointestinal digestion.
abstract: The milk fat globule membrane (MFGM) fraction refers to the thin film of polar lipids and membrane proteins that surrounds fat globules in milk. It is its unique biochemical composition that renders MFGM with some beneficial biological activities, such as anti-adhesive effects toward pathogens. However, a prerequisite for the putative bioactivity of MFGM is its stability during gastrointestinal digestion. We, therefore, subjected MFGM material, isolated from raw milk, to an in vitro enzymatic gastrointestinal digestion. Sodium dodecyl sulfate PAGE, in combination with 2 staining methods, Coomassie Blue and periodic acid Schiff staining, was used to evaluate polypeptide patterns of the digest, whereas mass spectrometry was used to confirm the presence of specific MFGM proteins. Generally, it was observed that glycoproteins showed higher resistance to endogenous proteases compared with non-glycosylated proteins. Mucin 1 displayed the highest resistance to digestion and a considerable part of this protein was still detected at its original molecular weight after gastric and small intestine digestion. Cluster of differentiation 36 was also quite resistant to pepsin. A significant part of periodic acid Schiff 6/7 survived the gastric digestion, provided that the lipid moiety was not removed from the MFGM material. Overall, MFGM glycoproteins are generally more resistant to gastrointestinal digestion than serum milk proteins and the presence of lipids, besides glycosylation, may protect MFGM glycoproteins from gastrointestinal digestion. This gastrointestinal stability makes MFGM glycoproteins amenable to further studies in which their putative health-promoting effects can be explored.
authors.affiliation: Department of Food Safety and Food Quality, Ghent University, Ghent, Belgium.
authors.forename: T T
authors.initials: TT
authors.lastname: Le
authors.forename: T
authors.initials: T
authors.lastname: Van de Wiele
authors.forename: T N H
authors.initials: TN
authors.lastname: Do
authors.forename: G
authors.initials: G
authors.lastname: Debyser
authors.forename: K
authors.initials: K
authors.lastname: Struijs
authors.forename: B
authors.initials: B
authors.lastname: Devreese
authors.forename: K
authors.initials: K
authors.lastname: Dewettinck
authors.forename: J
authors.initials: J
authors.lastname: Van Camp
mesh_terms: D000818:Animals; D002417:Cattle; D002918:Chymotrypsin / Q000378:metabolism; D004063:Digestion; D004591:Electrophoresis, Polyacrylamide Gel; D041981:Gastrointestinal Tract / Q000201:enzymology; D006017:Glycolipids / Q000378:metabolism*; D006023:Glycoproteins / Q000378:metabolism*; D006801:Humans; D066292:Lipid Droplets; D008565:Membrane Proteins / Q000378:metabolism*; D008894:Milk Proteins / Q000378:metabolism*; D008970:Molecular Weight; D018396:Mucin-1 / Q000378:metabolism; D010434:Pepsin A / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism
chemical_list: D006017:Glycolipids; D006023:Glycoproteins; D008565:Membrane Proteins; D008894:Milk Proteins; D018396:Mucin-1; C110367:milk fat globule; D010447:Peptide Hydrolases; D002918:Chymotrypsin; C117608:alpha-chymotrypsin; D014357:Trypsin; D010434:Pepsin A