Structural role of counterions adsorbed on self-assembled peptide nanotubes |
| |
Authors: | Gobeaux Frédéric Fay Nicolas Tarabout Christophe Mériadec Cristelle Meneau Florian Ligeti Melinda Buisson David-Alexandre Cintrat Jean-Christophe Nguyen Khac Minh Huy Perrin Lionel Valéry Céline Artzner Franck Paternostre Maïté |
| |
Institution: | Institut de Biologie et de Technologies de Saclay/Service de Bioénergétique, Biologie Structurale et Mécanismes, Commissariat à l'énergie Atomique et aux énergies Alternatives-Saclay, 91191 Gif-sur-Yvette, France. frederic.gobeaux@gmail.com |
| |
Abstract: | Among noncovalent forces, electrostatic ones are the strongest and possess a rather long-range action. For these reasons, charges and counterions play a prominent role in self-assembly processes in water and therefore in many biological systems. However, the complexity of the biological media often hinders a detailed understanding of all the electrostatic-related events. In this context, we have studied the role of charges and counterions in the self-assembly of lanreotide, a cationic octapeptide. This peptide spontaneously forms monodisperse nanotubes (NTs) above a critical concentration when solubilized in pure water. Free from any screening buffer, we assessed the interactions between the different peptide oligomers and counterions in solutions, above and below the critical assembly concentration. Our results provide explanations for the selection of a dimeric building block instead of a monomeric one. Indeed, the apparent charge of the dimers is lower than that of the monomers because of strong chemisorption. This phenomenon has two consequences: (i) the dimer-dimer interaction is less repulsive than the monomer-monomer one and (ii) the lowered charge of the dimeric building block weakens the electrostatic repulsion from the positively charged NT walls. Moreover, additional counterion condensation (physisorption) occurs on the NT wall. We furthermore show that the counterions interacting with the NTs play a structural role as they tune the NTs diameter. We demonstrate by a simple model that counterions adsorption sites located on the inner face of the NT walls are responsible for this size control. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|