Institut de Biologie et de Technologies de Saclay/Service de Bioénergétique, Biologie Structurale et Mécanismes, UMR 8221 CNRS and CEA, CEA-Saclay, 91191 Gif-sur-Yvette, France.
Langmuir. 2013 Feb 26;29(8):2739-45. doi: 10.1021/la304862f. Epub 2013 Feb 12.
Self-assembled nanoarchitectures based on biological molecules are attractive because of the simplicity and versatility of the building blocks. However, size control is still a challenge. This control is only possible when a given system is deeply understood. Such is the case with the lanreotide acetate, an octapeptide salt that spontaneously forms monodisperse nanotubes when dissolved into pure water. Following a structural approach, we have in the past demonstrated the possibility to tune the diameter of these nanotubes while keeping a strict monodispersity, either by chemical modification of one precise amino acid on the peptide sequence or by changing the size of the counterions. On the basis of these previous studies, we replaced monovalent counterions by divalent ones to vary the number of walls. Indeed, in the present work, we show that lanreotide associated with a divalent counterion forms double-walled nanotubes while keeping the average diameter constant. However, the strict monodispersity of the number of walls was unexpected. We propose that the divalent counterions create an adhesion force that can drive the wall packing. This adhesion force is counterbalanced by a mechanical one that is related to the stiffness of the peptide wall. By taking into account these two opposite forces, we have built a general model that fully explains why the lanreotide nanotubes formed with divalent counterions possess two walls and not more.
基于生物分子的自组装纳米结构由于其构建块的简单性和多功能性而具有吸引力。然而，尺寸控制仍然是一个挑战。只有当给定的系统被深入理解时，才有可能进行这种控制。醋酸兰瑞肽就是一个很好的例子，它是一种八肽盐，当溶解在纯水中时会自发形成单分散的纳米管。基于结构的方法，我们过去已经证明了通过化学修饰肽序列上的一个精确氨基酸或改变抗衡离子的大小来调节这些纳米管直径的同时保持严格的单分散性的可能性。在前述研究的基础上，我们用二价抗衡离子取代单价抗衡离子来改变壁的数量。事实上，在本工作中，我们表明，与二价抗衡离子结合的兰瑞肽形成了双壁纳米管，同时保持平均直径不变。然而，壁数的严格单分散性是出乎意料的。我们提出，二价抗衡离子产生的粘附力可以驱动壁的堆积。这种粘附力被与肽壁的刚性有关的机械力所平衡。通过考虑这两种相反的力，我们建立了一个通用模型，充分解释了为什么与二价抗衡离子形成的兰瑞肽纳米管具有两个壁而不是更多。
