Critical Role of Micelles in Pancreatic Lipase Activation Revealed by Small Angle Neutron Scattering*
Critical Role of Micelles in Pancreatic Lipase Activation Revealed by Small Angle Neutron Scattering*
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小角中子散射揭示胶束在胰腺脂肪酶激活中的关键作用*
DOI：
10.1074/jbc.275.6.4220
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
C. Chapus
中科院分区：
文献类型：
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作者：
D. Pignol;L. Ayvazian;B. Kerfelec;P. Timmins;I. Crenon;J. Hermoso;J. Fontecilla;C. Chapus
在十二指肠中，胰脂肪酶（PL）通过在其蛋白辅因子胰辅脂酶（PC）存在下与胆汁乳化油滴结合而对甘油三酯产生活性。PC-PL-胶束复合物的中子晶体结构（Hermoso，J.，Pampel，D.，Penel，S.，Roth，M.，Chapus，C.，和Fontecilla-Camps，J. C.（1997）EMBO J. 16，5531-5536）已经表明，酶在其活性构象中的稳定化及其对乳化油滴的吸附是由预先形成的脂肪酶-辅脂酶-胶束复合物介导的。在这里，我们将不同的两性化合物激活PL的能力与它们在溶液中与PC-PL的关联相关联。采用小角中子散射D2 O/H2O对比度变化法研究了PC-PL配合物与牛磺脱氧胆酸盐胶束的混合溶液。所得的回转半径（56 μ m）和溶液的匹配点表明形成了一种三元复合物，与中子晶体结构中观察到的类似。此外，我们表明，无论是胆汁盐，溶血磷脂，或非离子洗涤剂，形成胶束的回转半径范围从13至26 μ m能够结合到PC-PL复合物，而较小的胶束或非胶束化合物。这进一步支持了胶束大小依赖的亲合过程在体内激活脂肪酶的概念。
In the duodenum, pancreatic lipase (PL) develops its activity on triglycerides by binding to the bile-emulsified oil droplets in the presence of its protein cofactor pancreatic colipase (PC). The neutron crystal structure of a PC-PL-micelle complex (Hermoso, J., Pignol, D., Penel, S., Roth, M., Chapus, C., and Fontecilla-Camps, J. C. (1997) EMBO J. 16, 5531–5536) has suggested that the stabilization of the enzyme in its active conformation and its adsorption to the emulsified oil droplets are mediated by a preformed lipase-colipase-micelle complex. Here, we correlate the ability of different amphypathic compounds to activate PL, with their association with PC-PL in solution. The method of small angle neutron scattering with D2O/H2O contrast variation was used to characterize a solution containing PC-PL complex and taurodeoxycholate micelles. The resulting radius of gyration (56 Å) and the match point of the solution indicate the formation of a ternary complex that is similar to the one observed in the neutron crystal structure. In addition, we show that either bile salts, lysophospholipids, or nonionic detergents that form micelles with radii of gyration ranging from 13 to 26 Å are able to bind to the PC-PL complex, whereas smaller micelles or nonmicellar compounds are not. This further supports the notion of a micelle size-dependent affinity process for lipase activationin vivo.