Hernell O
Eur J Clin Invest. 1975 Jun 12;5(3):267-72. doi: 10.1111/j.1365-2362.1975.tb02294.x.
Human milk contains a bile salt-stimulated lipase in amounts that, at pH 6.5 and in the presence of bile salts, might account for a total hydrolysis of the milk triacylglycerols in less than 30 min. In the absence of bile salts the enzyme has no activity against milk fat or against emulsified trioleylglycerol. The primary bile salts sodium cholate and sodium chenodeoxycholate and their taurine and glycine conjugates, but not the secondary bile salt sodium deoxycholate or its taurine and glycine conjugates, caused a pronounced activation of the enzyme against emulsified trioleylglycerol. The lipase was stable at pH 3.5 and 37 degrees C for 1 hour. It was inactivated when incubated with trypsin or chymotrypsin at pH 6.5 but these inactivations were almost abolished in the presence of bile salts. High concentrations of pepsin slowly inactivated the enzyme at pH 4.0. The bile salt-stimulated lipase in human milk is thus stable enough to be active in the intestine, and it is present in high enough activity to contribute significantly to the hydrolysis of the milk triaclyglycerols in the intestine.
人乳中含有一定量的胆汁盐刺激脂肪酶，在pH 6.5且存在胆汁盐的情况下，该酶可能在不到30分钟的时间内将乳中的三酰甘油完全水解。在没有胆汁盐的情况下，该酶对乳脂肪或乳化三油酰甘油没有活性。初级胆汁盐胆酸钠和鹅去氧胆酸钠及其牛磺酸和甘氨酸结合物，而非次级胆汁盐脱氧胆酸钠或其牛磺酸和甘氨酸结合物，可显著激活该酶对乳化三油酰甘油的活性。该脂肪酶在pH 3.5和37℃下可稳定1小时。在pH 6.5下与胰蛋白酶或糜蛋白酶一起孵育时，该酶会失活，但在胆汁盐存在的情况下，这些失活作用几乎会被消除。高浓度的胃蛋白酶在pH 4.0时会使该酶缓慢失活。因此，人乳中的胆汁盐刺激脂肪酶足够稳定，能够在肠道中发挥活性，并且其活性足够高，能够对肠道中乳三酰甘油的水解做出显著贡献。
