Functionality of Bovive Milk Fat Globule Membrane

对牛乳脂肪球膜(MFGM)的功能性进行了研究：1)乳脂球(MFG)中MFGM的乳化能力；2)MFGM促进肠道对核黄素(RF)的吸收；3)抑制牛奶中脂蛋白脂肪酶(LPL)的脂解作用。1)将25%的乳脂和1%的MFGM在0.01M磷酸盐缓冲液(pH 7.0)中均质1min，在19k rpm和45℃下乳化1min，制备乳状液。当乳脂含量为25%、MFGM含量为1%、pH为中性、MFGM用量增加时，乳化液的乳化性能最好。影响MFG重组的主要因素是乳化时间、MFGM和乳脂含量以及pH。粘度在pH值为5.0、乳化时间为4min时最高，并随MFGM含量的增加而增加。吸附在MFG上的MFGM蛋白的组成不受主要变量的影响。但在酸性条件下，随着MFGM用量的增加，吸附蛋白质的量增加。MFG的直径为0.9…More-17.4um，中位直径为5.0um，比表面积为15.6m^2/m^3.2。对射频缺乏大鼠给予核黄素结合的MFGM(3mug/g饲料)，其谷胱甘肽还原酶活力比(EGRAR，+FAD/-FAD)为3.5。RF饲养后第5周，EGRAR恢复到1.6~1.9，体重增加。第5周体重增加50.2++3.8g，40.4++3.9g，33.1++5.4g。3组间差异有统计学意义(P&lt；0.01)。MFGM可促进大鼠肠道对RF的吸收。(3)乳清蛋白(Lactophrin，LP)是从乳清中分离得到的，在免疫学上与MFGM的可溶性糖蛋白(SGP)相同。在200W超声作用2min的新鲜牛乳中加入Lp，可抑制乳脂酶诱导的脂解作用。在每毫升牛奶中加入40 mg蛋白时，对乳清蛋白的抑制率约为62-67%，对富含乳清蛋白的组分-3的抑制率为30-43%。LP和SGP似乎通过增强对MFG表面的补充力来抑制LPL的脂解作用。较少

We studied on the functionality of bovine milk fat globule membrane (MFGM) with special reference to 1) the emusifying ability of MFGM in milk fat globules (MFG), 2) the acceleration of intestinal absorption of riboflavin (RF) by MFGM and 3) inhibition of lipolysis due to lipoprotein lipase (LPL) in milk.1) MFG emulsions were reconstituted by homogenizing 25% milk fat and 1% MFGM in 0.01M phosphate buffer (pH 7.0) for 1 min at 19 k rpm and at 45^0C. Maximal emulsifying properties were attained at 25% milk fat, 1% MFGM, neutral pH and the increased amount of MFGM. The major variables influencing the reconstitution of MFG were emulsifying time, MFGM and milk fat contents, and pH. Viscosity was highest at pH 5.0 and at 4 min of emulsifying time, and increased with MFGM content. The composition of MFGM protein adsorbed on MFG was not affected by the major variables. However, the amount of adsorbed protein increased at acidic pH and with the increased amount of MFGM. Diameter of MFG was 0.9 … More -17.4mum and median diameter was 5.0mum and its specific surface area was 15.6 m^2/m^3.2) Riboflavin bound MFGM was administered (3mug/g of diet) TO RF-defficient rats in who glutathion reductase activity ration (EGRAR, +FAD/-FAD) was 3.5, in comparison with free RF, after RF deprivation for 4 weeks. After RF feeding, EGRAR recovered to 1.6-1.9 and body weights increased in the fifth weeks. Gain of body weights for 1 week in the fifth weeks was 50.2<plus-minus>3.8 g for MFGM-RF-fed group, 40.4<plus-minus>3.9 g for free RF-fed group, and 33.1<plus-minus>5.4 g for pair-fed group. Significant differences were found among 3 groups (P<0.0 1). MFGM seemed to accelerate the absorption of RF from the intestine of rats. The peptides from MFGM may act as a signal peptide for the acceleration of the incorporating RF from intestinal mem3) Lactophrin (LP), which is immunologically identical to the soluble glycoprotein (SGP) of MFGM, was isolated from milk whey. LP added in fresh bovine milk sonicated for 2 min at 200 W inhibited the lipolysis induced by milk indigeneus LPL. The ratio of inhibition was about 62-67% for LP and 30-43% for the LP- enriched component-3 fraction of proteose-peptone at 40 mg of protein/ml of milk over the control. LP and SGP seemed to be inhibited the lipolytic action of LPL by a high ability to replenish the surface of MFG. Less