How colipase fatty acid interactions mediate adsorption of pancreatic lipase to interfaces
How colipase fatty acid interactions mediate adsorption of pancreatic lipase to interfaces
复制标题
DOI：
10.1021/bi973015r
复制
发表时间：
1998-06-09
期刊：
影响因子：
2.9
通讯作者：
Brockman, H
中科院分区：
文献类型：
--
作者：
Dahim, M;Brockman, H
辅脂酶是一种与胰脂肪酶形成1：1复合物的辅因子蛋白。这有利于脂肪酶吸附到富含磷脂酰胆碱的界面，大概是由于这种界面的辅脂酶的亲和力较高。根据该模型，辅脂酶在界面中的存在应足以使脂肪酶从水相吸附。为了验证这一假设，将氩-缓冲液界面处的辅脂酶、磷脂酰胆碱和脂肪酸的混合单层暴露于注入搅拌的水相亚相中的脂肪酶。扩散的辅脂酶仍然与脂质单层的表面压力和脂质成分依赖性的方式。例如，单独使用二酰基磷脂酰胆碱时，辅脂酶在表面压力120 mN/m下保留在脂质单层中，但使用纯脂肪酸时，这增加到接近40 mN/m。与现有的范例相反，在脂质单层中存在辅脂酶不足以使脂肪酶吸附到界面。脂肪酸也是必需的，并且其增强脂肪酶吸附的能力超过在不存在辅脂酶的情况下观察到的能力取决于脂肪酸和辅脂酶的摩尔分数。这些结果支持的假设，辅脂酶集中脂肪酸横向在其周边，并建议，连同脂肪酶-辅脂酶相互作用，富含脂肪酸的纳米结构域周围辅脂酶促进脂肪酶吸附在“皮瓣打开”的构象。
Colipase is a cofactor protein which forms a 1:1 complex with pancreatic lipase. This facilitates lipase adsorption to phosphatidylcholine-rich interfaces, presumably as a consequence of the higher affinity of colipase for such interfaces. According to this model, the presence of colipase in an interface should be sufficient to enable lipase adsorption from the aqueous phase. To test this hypothesis, mixed monolayers of colipase, phosphatidylcholine, and fatty acid at the argon-buffer interface were exposed to lipase injected into the stirred aqueous subphase. Spread colipase remained associated with the lipid monolayer in a surface pressure-and lipid composition-dependent manner. For example, with diacylphosphatidyl-choline alone, colipase remained in the lipid monolayer at surface pressures 120 mN/m, but with pure fatty acid this was increased to similar to 40 mN/m. Contrary to the existing paradigm, the presence of colipase in a lipid monolayer was not sufficient to enable the adsorption of lipase to the interface. Fatty acid was also required, and its ability to enhance lipase adsorption over that observed in the absence of colipase was dependent on the fatty acid and colipase mole fractions. These results support the hypothesis that colipase concentrates fatty acids laterally at its periphery and suggest that, together with lipase-colipase interaction, the fatty acid-rich nano-domain surrounding colipase facilitates lipase adsorption in the 'flap-opened' conformation.