Pignol D, Hermoso J, Kerfelec B, Crenon I, Chapus C, Fontecilla-Camps J C
Laboratoire de Cristallographie et de Cristallogenèse des Protéines, Institut de Biologie Structurale Jean-Pierre Ebel, CEA-CNRS, Grenoble, France.
Chem Phys Lipids. 1998 Jun;93(1-2):123-9. doi: 10.1016/s0009-3084(98)00036-x.
The catalytic activity of most lipases depends on the aggregation state of their substrates. It is supposed that lipase activation requires the unmasking and structuring of the enzyme's active site through conformational changes involving the presence of oil-in-water droplets. This phenomenon has been called interfacial activation. Here, we report the crystal structure of the pancreatic activated lipase/colipase/micelle complex as determined using the D2O/H2O contrast variation low resolution neutron diffraction method. We find that a disk-shaped micelle interacts extensively with the concave face of colipase (CL) and the distal tip of the C-terminal domain of lipase away from the active site of the enzyme. Such interaction appears to help stabilizing the lipase-CL interaction. Consequently, we conclude that lipase activation is not interfacial but occurs in the aqueous phase and it is mediated by CL and a micelle.
大多数脂肪酶的催化活性取决于其底物的聚集状态。据推测，脂肪酶的激活需要通过涉及水包油液滴存在的构象变化来揭示酶的活性位点并使其结构化。这种现象被称为界面激活。在此，我们报告了使用重水/水对比变化低分辨率中子衍射方法测定的胰腺激活脂肪酶/辅脂肪酶/胶束复合物的晶体结构。我们发现，盘状胶束与辅脂肪酶（CL）的凹面以及脂肪酶C末端结构域远离酶活性位点的远端广泛相互作用。这种相互作用似乎有助于稳定脂肪酶 - CL相互作用。因此，我们得出结论，脂肪酶的激活不是在界面发生，而是在水相中发生，并且由CL和胶束介导。
