Vauthey Sylvain, Santoso Steve, Gong Haiyan, Watson Nicki, Zhang Shuguang
Center for Biomedical Engineering, 56-341, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA.
Proc Natl Acad Sci U S A. 2002 Apr 16;99(8):5355-60. doi: 10.1073/pnas.072089599. Epub 2002 Apr 2.
Several surfactant-like peptides undergo self-assembly to form nanotubes and nanovesicles having an average diameter of 30-50 nm with a helical twist. The peptide monomer contains 7-8 residues and has a hydrophilic head composed of aspartic acid and a tail of hydrophobic amino acids such as alanine, valine, or leucine. The length of each peptide is approximately equal to 2 nm, similar to that of biological phospholipids. Dynamic light-scattering studies showed structures with very discrete sizes. The distribution becomes broader over time, indicating a very dynamic process of assembly and disassembly. Visualization with transmission electron microscopy of quick-freeze/deep-etch sample preparation revealed a network of open-ended nanotubes and some vesicles, with the latter being able to "fuse" and "bud" out of the former. The structures showed some tail sequence preference. Many three-way junctions that may act as links between the nanotubes have been observed also. Studies of peptide surfactant molecules have significant implications in the design of nonlipid biological surfactants and the understanding of the complexity and dynamics of the self-assembly processes.
几种表面活性剂样肽会进行自组装，形成平均直径为30 - 50 nm且呈螺旋扭曲的纳米管和纳米囊泡。肽单体含有7 - 8个残基，具有由天冬氨酸组成的亲水头和由丙氨酸、缬氨酸或亮氨酸等疏水氨基酸组成的尾。每个肽的长度约等于2 nm，与生物磷脂的长度相似。动态光散射研究显示结构具有非常离散的尺寸。随着时间推移，分布变宽，表明组装和解组装是一个非常动态的过程。对快速冷冻/深度蚀刻样品制备进行透射电子显微镜观察发现了开放式纳米管网络和一些囊泡，后者能够从前者“融合”并“出芽”。这些结构表现出一些尾序列偏好。还观察到许多可能作为纳米管之间连接的三叉路口。肽表面活性剂分子的研究在非脂质生物表面活性剂的设计以及对自组装过程的复杂性和动态性的理解方面具有重要意义。
