Bernbäck S, Bläckberg L, Hernell O
Department of Physiological Chemistry, University of Umeå, Sweden.
Biochim Biophys Acta. 1989 Feb 20;1001(3):286-93. doi: 10.1016/0005-2760(89)90113-6.
The concerted action of purified bovine gastric lipase and human pancreatic colipase-dependent lipase and colipase, or crude human pancreatic juice, in the digestion of human milk triacylglycerols was explored in vitro. Gastric lipase hydrolyzed milk triacylglycerol with an initially high rate but became severely inhibited already at low concentration of released fatty acid. In contrast, colipase-dependent lipase could not, by itself, hydrolyze milk triacylglycerol. However, a short preincubation of milk with gastric lipase, resulting in a limited lipolysis, made the milk fat triacylglycerol available for an immediate and rapid hydrolysis by pancreatic juice, and also for purified colipase-dependent lipase, provided colipase and bile salts were present. The same effect was obtained when incubation with gastric lipase was replaced by addition of long-chain fatty acid. Long-chain fatty acid increased the binding of colipase-dependent lipase to the milk fat globule. Binding was efficient only in the presence of both fatty acid and colipase. We conclude that a limited gastric lipolysis of human milk triacylglycerol, resulting in a release of a low concentration of long-chain fatty acids, is of major importance for the subsequent hydrolysis by colipase-dependent lipase in the duodenum.
在体外研究了纯化的牛胃脂肪酶、人胰辅脂酶依赖性脂肪酶和辅脂酶，或人胰粗酶液对人乳三酰甘油消化的协同作用。胃脂肪酶以最初较高的速率水解乳三酰甘油，但在释放的脂肪酸浓度较低时就受到严重抑制。相比之下，辅脂酶依赖性脂肪酶本身不能水解乳三酰甘油。然而，将乳与人胃脂肪酶进行短时间预孵育，导致有限的脂解作用，使得乳脂肪三酰甘油可被胰液立即快速水解，并且如果存在辅脂酶和胆汁盐，也可被纯化的辅脂酶依赖性脂肪酶水解。当用添加长链脂肪酸代替与人胃脂肪酶孵育时，可获得相同的效果。长链脂肪酸增加了辅脂酶依赖性脂肪酶与乳脂肪球的结合。只有在脂肪酸和辅脂酶都存在的情况下，结合才有效。我们得出结论，人乳三酰甘油的有限胃脂解作用导致低浓度长链脂肪酸的释放，这对于十二指肠中辅脂酶依赖性脂肪酶随后的水解至关重要。
