Bernbäck S, Bläckberg L, Hernell O
Department of Physiological Chemistry, University of Umeå, Sweden.
J Clin Invest. 1990 Apr;85(4):1221-6. doi: 10.1172/JCI114556.
Gastric lipase, pancreatic colipase-dependent lipase, and bile salt-stimulated lipase all have potential roles in digestion of human milk triacylglycerol. To reveal the function of each lipase, an in vitro study was carried out with purified lipases and cofactors, and with human milk as substrate. Conditions were chosen to resemble those of the physiologic environment in the gastrointestinal tract of breast-fed infants. Gastric lipase was unique in its ability to initiate hydrolysis of milk triacylglycerol. Activated bile salt-stimulated lipase could not on its own hydrolyze native milk fat globule triacylglycerol, whereas a limited hydrolysis by gastric lipase triggered hydrolysis by bile salt-stimulated lipase. Gastric lipase and colipase-dependent lipase, in combination, hydrolyzed about two thirds of total ester bonds, with monoacylglycerol and fatty acids being the end products. Addition of bile salt-stimulated lipase resulted in hydrolysis also of monoacylglycerol. When acting together with colipase-dependent lipase, bile salt-stimulated lipase contributed also to digestion of tri- and diacylglycerol. We conclude that digestion of human milk triacylglycerol depends on three lipases with unique, only partly overlapping, functions. Their concerted action results in complete digestion with free glycerol and fatty acids as final products.
胃脂肪酶、胰辅脂酶依赖性脂肪酶和胆汁盐刺激脂肪酶在人乳三酰甘油的消化过程中均具有潜在作用。为了揭示每种脂肪酶的功能，我们使用纯化的脂肪酶、辅因子以及人乳作为底物进行了一项体外研究。实验条件的选择旨在模拟母乳喂养婴儿胃肠道的生理环境。胃脂肪酶在启动乳三酰甘油水解方面具有独特能力。活化的胆汁盐刺激脂肪酶自身无法水解天然乳脂肪球三酰甘油，而胃脂肪酶引发的有限水解会触发胆汁盐刺激脂肪酶的水解作用。胃脂肪酶和辅脂酶依赖性脂肪酶共同作用可水解约三分之二的总酯键，最终产物为单酰甘油和脂肪酸。添加胆汁盐刺激脂肪酶会导致单酰甘油也被水解。当与辅脂酶依赖性脂肪酶共同作用时，胆汁盐刺激脂肪酶也有助于三酰甘油和二酰甘油的消化。我们得出结论，人乳三酰甘油的消化依赖于三种功能独特但部分重叠的脂肪酶。它们的协同作用导致以游离甘油和脂肪酸作为最终产物的完全消化。
