Department of Physics, Kindai University, 3-4-1 Kowakae Higashiosaka, Osaka, 577-8502, Japan.
Department of Chemistry, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8571, Japan.
Anal Sci. 2021 Nov 10;37(11):1505-1509. doi: 10.2116/analsci.21P068. Epub 2021 Apr 16.
X-ray reflectivity measurements were performed for the leucine and lysine-based LKα14 peptide designed to adopt an α-helical conformation at the air-water interface. The electron density profiles along the surface normal were calculated from the atomic coordinates predicted by an electronic structure program to fit the X-ray reflectivity curve. At the concentration of the monolayer formation, the long axis of the α-helix adsorbed parallel to the water surface, and the central part was revealed to be submerged in water. On the other hand, at 100 times higher than the surface area density of the monolayer formation, the double layer is formed in which the long axis of the α-helix is parallel to the water surface and only the peptide in the second layer is submerged in water.
X 射线反射率测量是针对设计为在气-水界面处采用α-螺旋构象的亮氨酸和赖氨酸基 LKα14 肽进行的。根据电子结构程序预测的原子坐标，沿表面法线计算电子密度分布，以拟合 X 射线反射率曲线。在单层形成的浓度下，α-螺旋的长轴平行于水面吸附，中心部分被揭示为浸入水中。另一方面，在比单层形成的表面积密度高 100 倍的情况下，形成了双层，其中α-螺旋的长轴平行于水面，只有第二层的肽浸入水中。
