Exploring the peptide nanotube formation from the self-assembly of the Aβ(13-21)K16A peptide in the presence of Zinc ions Public

Abstract

In vitro, Zn²⁺ accelerates the self-assembly of Aβ(13-21)K16A and induces the formation of ribbons (Dong 2006). Peptide ribbons have been proposed to be the precursors of peptide nanotubes. Theoretically, the peptide ribbons formed by Aβ(13-21)K16A can also change to peptide nanotubes. In this dissertation, temperature effects of the self-assembly of Aβ(13-21)K16A were investigated in the presence of zinc ions. In the presence of zinc ions, Aβ(13-21)K16A peptides self assemble into ribbons at low temperature, such as 4 ^oC and 24 ^oC. When increasing the temperature to 37 ^oC, these peptides self assemble into peptide nanotubes. Preformed helical ribbons can switch to peptide nanotubes with increasing temperature. Peptide nanotubes are quiet stable, and they cannot dissemble back to helical ribbons. The transaction from helical ribbons to peptide nanotubes possibly attributes to the dramatic expansion of sheet-sheet lamination. ssNMR experiments have been tried to clarify the detail peptide arrangement in zinc induced Aβ(13-21)K16A peptide nanotubes. Cryo- and lyo- experiments show that peptide nanotubes are destroyed during lyophilization. To protect the peptide nanotubes, several anions and chelates, such as SO4^2-, EDTA, terephthalic acid, hydroquinone, 1,2-ethanedithiol and 1,4-benzenedimethanethiol, have been tested to bundle the tubes. All these reagents cannot bundle the peptide nanotubes successfully. Solvent effects on the Zn²⁺ induced Aβ(13-21)K16A peptide self-assembly have been investigated to study the physical stability of peptide nanotubes. The results show that some solvents, such as methanol and acetonitrile, can destabilize the peptide nanotubes. The higher the solvent concentration, the less stable the peptide nanotubes. Temperature effect of the peptide self-assembly at certain solvent concentrations indicates that Zn²⁺ induced ribbons or nanotubes are more stable at lower temperature in the presence of acetonitrile. The assembled peptide nanotubes, with such ordered and dense packed Zn²⁺ sites exposed on the surface, open the possibility to engineer temperature directed polymerization and unique catalytic chemistry.

Table of Contents

TABLE OF CONTENTS ACKNOWLEDGEMENTS LIST OF FIGURES LIST OF TABLES LIST OF ABBREVIATIONS CHAPTER 1 1. INTRODUCTION 2. PROTEIN BASED NANOMATERIALS 3. AMYLOID BETA PEPTIDE 4. ZINC EFFECT IN AMYLOID FORMATION CHAPTER 2 EXPLORING THE PEPTIDE NANOTUBE FORMATION FROM SELF-ASSEMBLY OF THE Aβ(13-21)K16A PEPTIDE IN THE PRESENCE OF ZINC IONS 1. INTRODUCTION 2. MATERIALS AND METHODS 3. RESULTS (1) Temperature changes Zn²⁺-induced Aβ(13-21)K16A self-assembly (2) Peptide arrangement in Zinc induced peptide nanotube (3) Stability of Zn²⁺-induced Aβ(13-21)K16A peptide nanotubes 4. CONCLUSION CHAPTER 3 CONCLUSIONS AND PERSPECTIVES REFERENCES

About this Dissertation

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School	Laney Graduate School
Department	Chemistry
Degree	MS
Submission	Dissertation
Language	English
Research Field	Chemistry, Biochemistry Chemistry, Analytical
Mot-clé	zinc self-assembly peptide nanotube amyloid peptide
Committee Chair / Thesis Advisor	Lynn, David, Emory University
Committee Members	Conticello, Vincent, Emory University Lutz, Stefan, Emory University

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