Relationship between activity of some fat globule membrane enzymes and the lipidic fraction in ewes' milk: Preliminary studies

Fat globule membranes in ewes' milk: The main enzyme activities during lactation

“…1). In addition, a negative correlation between XO and the diameter of MFGs (À0.159; P 0.01) was found, confirming the positive link between XO and smaller globules reported in a previous study (Martini et al, 2010). This suggests that the link between XO and the diameter of MFGs is probably due to the fact that the enzyme XOR could be involved in the secretion of the globules (McManaman, Russell, Schaack, Orlicky, & Robenek, 2007).…”

“…The MFGM consists of a single inner layer originating from the endoplasmic reticulum and a double layer, arising from the membrane of the secretory cell (Mather & Keenan, 1998). The amount of MFGM in milk changes depending on the number and diameter of globules (Martini, Salari, Pesi, & Tozzi, 2010). The MFGM supplies many proteins and enzymes, some of which have beneficial biological effects (Dewettinck et al, 2008), whereas others have been linked to human diseases (Riccio, 2004).…”

“…Research on MFGMs has mainly been carried out on cows' and human milk (Liao, Alvarado, Phinney & Lönnerdal, 2011;Mather, 2000), whereas there have only been a few studies on MFGM proteins in sheep (Martini et al, 2010;Pisanu et al, 2011).…”

Evaluation of the fatty acid profile from the core and membrane of fat globules in ewe's milk during lactation

“…Although the fat globule membranes (MFGMs) are minor components of fat compared to the triglycerides of the core (approximately 98% of fat), the membrane content in milk changes depending on the number and diameter of globules (Martini, Salari, Pesi, & Tozzi, 2010) and thus on the changes in the core/membrane ratio (Briard et al, 2003;Martini et al, 2010).…”

The effect of heat treatment on γ-glutamyl transferase activity in non-bovine and bovine milk – A comparative kinetic and thermodynamic investigation

“…The membrane spanning enzyme g-glutamyl transpeptidase or g-glutamyl transferase (GGT) (EC 2.3.2.2) catalyzes the breakdown of the tripeptide glutathione using its g-glutamyl moiety as a shuttle to transport free amino acids across the membrane into the cell (Martini, Salari, Pesi, & Tozzi, 2010). GGT is involved in the transportation of the amino acids from blood to mammary glands, playing an important role for biosynthesis of milk proteins.…”