Brockman H L
The Hormel Institute, University of Minnesota, 801 NE 16th Avenue, MN 55912, Austin, USA.
Biochimie. 2000 Nov;82(11):987-95. doi: 10.1016/s0300-9084(00)01185-8.
Pancreatic lipase is a surface-active protein that binds avidly to interfaces comprised of the substrates and products of lipolysis. However, both lipase binding to substrate-containing particles and subsequent interfacial catalysis are inhibited by a number of amphipathic molecules. The most thoroughly studied of these, phosphatidylcholine, is a common constituent of membranes and intestinal lipid contents. Colipase, a surface-active cofactor of lipase, relieves inhibition by phosphatidylcholine in several ways. Through protein-protein interactions, colipase helps anchor lipase to surfaces and stabilizes it in the open conformation. Within the interface, colipase packs more efficiently with substrates and products of lipolysis than with phosphatidylcholine, thereby concentrating these reactants in the vicinity of colipase. This enrichment of lipase substrates and products in the vicinity of colipase enhances lipase-lipid interactions. The result is that colipase facilitates the adsorption of lipase to the interface and, possibly, increases the availability of substrate to the enzyme. Thus, the functional unit in intestinal lipolysis appears to be a lipase-colipase-reactant complex.
胰脂肪酶是一种表面活性蛋白，它能与由脂肪分解的底物和产物构成的界面紧密结合。然而，脂肪酶与含底物颗粒的结合以及随后的界面催化都会受到多种两亲性分子的抑制。其中研究最为深入的是磷脂酰胆碱，它是细胞膜和肠道脂质成分的常见组成部分。辅脂酶是脂肪酶的一种表面活性辅因子，它通过多种方式解除磷脂酰胆碱的抑制作用。通过蛋白质 - 蛋白质相互作用，辅脂酶有助于将脂肪酶锚定在表面，并使其稳定在开放构象。在界面内，辅脂酶与脂肪分解的底物和产物的结合比与磷脂酰胆碱的结合更有效，从而将这些反应物集中在辅脂酶附近。辅脂酶附近脂肪酶底物和产物的这种富集增强了脂肪酶与脂质的相互作用。结果是辅脂酶促进了脂肪酶在界面的吸附，并且可能增加了酶对底物的可及性。因此，肠道脂肪分解中的功能单元似乎是脂肪酶 - 辅脂酶 - 反应物复合物。
