Boncheva M, Vogel H
Institute of Physical Chemistry, Swiss Federal Institute of Technology, Lausanne, Switzerland.
Biophys J. 1997 Aug;73(2):1056-72. doi: 10.1016/S0006-3495(97)78138-4.
The molecular self-organization and structural properties of peptide assemblies at different interfaces, using either amphipathic or hydrophobic polypeptide helices, is described. The two peptides under investigation form stable monolayers on the water surface under the conservation of their molecular conformation, as studied by circular dichroism and polarization-modulation Fourier transform infrared (FTIR) spectroscopy. Using surface plasmon resonance and reflection-absorption FTIR, we show that such molecular layers can be transferred unaltered to solid substrates. Most importantly, the molecular orientation of the hydrophobic helices on solid supports such as gold can be controlled by choosing a particular procedure for the layer formation. The helices were oriented parallel to the interface in Langmuir-Blodgett monolayers, and perpendicular to the interface in self-assembled monolayers. Our reflection-absorption FTIR measurements have delivered for the first time direct experimental evidence for the molecular conformation and orientation of pure peptide monolayers. Suitable reference spectra of polypeptides with defined conformation and orientation are necessary to use this technique for the determination of the molecular orientation of peptides in monomolecular films. We have solved the problem for alpha-helical polypeptides by using bacteriorhodopsin as a reference in combination with synthetic alpha-helices of defined interfacial orientation. The present study shows the possibility of constructing immobilized peptide monolayers with predefined macroscopic properties and molecular structure by choosing the proper polypeptide amino acid sequence, the technique used for layer formation, and the supporting surface properties.
本文描述了使用两亲性或疏水性多肽螺旋在不同界面上肽组装体的分子自组装和结构特性。通过圆二色性和偏振调制傅里叶变换红外（FTIR）光谱研究发现，所研究的两种肽在保持其分子构象的情况下在水表面形成稳定的单分子层。利用表面等离子体共振和反射吸收FTIR，我们表明这样的分子层可以完整地转移到固体基质上。最重要的是，通过选择特定的成膜程序，可以控制疏水性螺旋在诸如金等固体支持物上的分子取向。在Langmuir-Blodgett单分子层中，螺旋平行于界面取向，而在自组装单分子层中垂直于界面取向。我们的反射吸收FTIR测量首次为纯肽单分子层的分子构象和取向提供了直接的实验证据。为了使用该技术测定单分子膜中肽的分子取向，需要具有确定构象和取向的多肽的合适参考光谱。我们通过使用细菌视紫红质作为参考并结合具有确定界面取向的合成α-螺旋，解决了α-螺旋多肽的问题。本研究表明，通过选择合适的多肽氨基酸序列、成膜技术和支持表面性质，可以构建具有预定义宏观性质和分子结构的固定化肽单分子层。
