Fat globule membranes

Lactadherin is a glycoprotein produced by mammary epithelial cells during lactation and associated with the milk fat globule membrane (Newburg et ah, 1998). Its concentration in milk peaks at 0.139 mg/ml immediately postpartum and declines thereafter (reviewed by Kvistgaard et ah, 2004). It has been reported to bind to human Rotavirus,... 

Schroten, H., Hanisch, F. G., Plogmann, R., Hacker, J., Uhlenbruck, G., Nobis-Bosch, R., and Wahn, V. (1992). Inhibition of adhesion of S-fimbriated Escherichia coli to buccal epithelial cells by human milk fat globule membrane components A novel aspect of the protective function of mucins in the nonimmunoglobulin fraction. Infect. Immun. 60,2893-2899. 

King, N. "The Milk Fat Globule Membrane", Comm. Agr. Bur., Farnham Royal, Bucks, England, 1955. 

Table 3.9 Gross composition of the milk fat globule membrane...

Table 3.10 Composition of bovine milk fat globule membranes...

Table 3.12 Enzymatic activities detected in bovine milk fat globule membrane preparations...

Figure 3.18 Schematic representation of a trilaminar cell membrane which is derived from the apical membrane of the mammary cell and forms the outer layer of the milk fat globule membrane following expression from the mammary cell, but which is more or less extensively lost on ageing. 1, phospholipid/glycolipid 2, protein 3, glycoprotein.

Isolation and characterization. Alkaline phosphatase is concentrated in the fat globule membrane and hence in cream. It is released into the buttermilk on phase inversion consequently, buttermilk is the starting material for most published methods for the purification of alkaline phosphatase. Later methods have used chromatography on various media to give a homogeneous preparation with 7440-fold purification and 28% yield. The characteristics of milk alkaline phosphatase are summarized in Table 8.2. The enzyme appears to be similar to the alkaline phosphatase of mammary tissue. 

Milks of most species contain more water than any other constituent. Certainly this is true of the milks consumed by humans. The other constituents are dissolved, colloidally dispersed, and emulsified in water. The dissolved solutes in bovine milk aggregate about 0.3 M and depress the freezing point by about 0.54°C (see Chapter 8). The activity of water in milk, aw, which is the ratio of its vapor pressure to that of air saturated with water, is about 0.993. A small amount of the water of milk is bound , o tightly by proteins and by the fat globule membrane that it does not function as a solvent for small molecules and ions. Water content is usually determined as loss in weight upon drying under conditions that minimize decomposition of organic constituents, e.g., 3 hr at 98-100°C (Horwitz 1980). 

The distribution of trace elements among the compounds and physical phases in milk has not been elucidated completely. Molybdenum appears to be found exclusively in xanthine oxidase and Co in vitamin B12. Iron is an essential component of xanthine oxidase, lactoperoxi-dase, and catalase. About half of the total Fe and 10% of the Cu are in the fat globule membrane. Copper has been studied extensively in relation to oxidation of milk lipids. The trace metal present in highest con-... 

Except for bovine serum albumin, immunoglobulins, and fat globule membrane proteins, the nomenclature employed in this classification consists of the use of a Greek letter, with or without a numerical sub-... 

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