Parker Roger, Rigby Neil M, Ridout Michael J, Gunning A Patrick, Wilde Peter J
Institute of Food Research, Norwich Research Park, Colney, Norwich, NR4 7UA, UK.
Soft Matter. 2014 Sep 14;10(34):6457-66. doi: 10.1039/c4sm01093k.
The digestion of dietary components in the human gastrointestinal (GI) tract is a complex, dynamic, inherently heterogeneous process. A key aspect of the digestion of lipid in the GI tract is the combined action of bile salts, lipase and colipase in hydrolysing and solubilising dispersed lipid. The bile salts are a mixture of steroid acid conjugates with surfactant properties. In order to examine whether the different bile salts have different interfacial properties their dynamic interfacial behaviour was characterised. Differences in the adsorption behaviour to solid hydrophobic surfaces of bile salt species were studied using dual polarisation interferometry and atomic force microscopy (AFM) under physiological conditions. Specifically, the cholates adsorbed more slowly and a significant proportion were irreversibly adsorbed following buffer rinsing; whereas the deoxycholates and chenodeoxycholates adsorbed more rapidly and desorbed to a greater extent following buffer rinsing. The conjugating groups (taurine, glycine) did not influence the behaviour. AFM showed that the interfacial structures that remained following buffer rinsing were also different between these two groups. In addition, the adsorption-desorption behaviour affected the adsorption of colipase to a solid surface. This supports the idea that cooperative adsorption occurs between certain bile salts and colipase to facilitate the adsorption and activity of pancreatic lipase in order to restore lipolytic activity in the presence of bile salts. This study provides insights into how differences in bile salt structure could affect lipase activity and solubilisation of lipolysis products and other lipid-soluble bioactive molecules.
人类胃肠道（GI）中膳食成分的消化是一个复杂、动态且本质上异质的过程。胃肠道中脂质消化的一个关键方面是胆汁盐、脂肪酶和辅脂肪酶在水解和溶解分散脂质方面的协同作用。胆汁盐是具有表面活性剂特性的类固醇酸共轭物的混合物。为了研究不同的胆汁盐是否具有不同的界面性质，对它们的动态界面行为进行了表征。在生理条件下，使用双偏振干涉测量法和原子力显微镜（AFM）研究了胆汁盐种类在固体疏水表面上的吸附行为差异。具体而言，胆酸盐吸附较慢，并且在缓冲液冲洗后有很大一部分不可逆吸附；而脱氧胆酸盐和鹅脱氧胆酸盐吸附较快，并且在缓冲液冲洗后解吸程度更大。共轭基团（牛磺酸、甘氨酸）不影响该行为。AFM显示，缓冲液冲洗后残留的界面结构在这两组之间也有所不同。此外，吸附 - 解吸行为影响了辅脂肪酶在固体表面的吸附。这支持了这样一种观点，即某些胆汁盐和辅脂肪酶之间会发生协同吸附，以促进胰腺脂肪酶的吸附和活性，从而在胆汁盐存在的情况下恢复脂解活性。这项研究深入探讨了胆汁盐结构的差异如何影响脂肪酶活性以及脂解产物和其他脂溶性生物活性分子的溶解。
