Thermodynamic and Kinetic Study of the Fibrillization of a Family of Tetrapeptides and Its Application to Self-Sorting. What Takes So Long?
| Autor: | Ashkan Dehsorkhi, Valeria Casttelleto, Marta Tena-Solsona, Ian W. Hamley, Beatriu Escuder, Juan F. Miravet |
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| Rok vydání: | 2015 |
| Předmět: |
Thermodynamic parameter
General Chemical Engineering Potentiometric titration Kinetics Peptide Potentiometric titrations symbols.namesake Amyloid disease Potentiometers (electric measuring instruments) Computational chemistry Kinetic and thermodynamic parameters Materials Chemistry Side chain Organic chemistry Free energy Solubility Fluorescence spectroscopy Kinetically controlled chemistry.chemical_classification Agglomeration Phenylalanine residues General Chemistry Self assembled fibrillar networks Gibbs free energy Titration chemistry Aspartic acid residues Thermodynamics and kinetics symbols Amino acids Thermodynamics Voltammetry Peptides |
| Zdroj: | Chemistry of Materials. 27:3358-3365 |
| ISSN: | 1520-5002 0897-4756 |
| DOI: | 10.1021/acs.chemmater.5b00580 |
| Popis: | Insight is provided into the thermodynamics and kinetics of peptide fibrillization, a process of particular interest in biomedicine due to its direct relationship to amyloid diseases. The studied isomeric tetrapeptides are terminally end-capped and present two hydrophobic phenylalanine residues and two ionizable hydrophilic aspartic acid residues. These compounds form gels in water which are composed of self-assembled fibrillar networks. Potentiometric titrations have afforded acid-base and solubility constants associated with the fibrillization process. A remarkable pKa shift of the peptide side chains is observed linked to aggregation, allowing for fiber formation at pH values around neutrality. The magnitude of the pKa shift is directly related to the solubility of the tetrapeptides, namely, to the free energy change associated with fibrillization. Therefore, potentiometric titration emerges as a simple tool to evaluate the thermodynamic parameters of the process. Additionally kinetic measurements with NMR, fluorescence spectroscopy, and SANS reveal that initial peptide dimerization is most likely to be the fibrillization rate-determining step. The aggregation process in all cases presents a relatively long lag time of ca. 1-3 h and takes more than 8 h to complete. No correlation is observed between kinetic and thermodynamic parameters. Finally, kinetically controlled self-sorting of a mixture of two isomeric tetrapeptides is described. © 2015 American Chemical Society. M.T.-S., B.E., and J.F.M. thank the Ministry of Science and Innovation of Spain (Grant CTQ2012-37735) and Universitat Jaume I (Grants P1.1B2012-25 and P1.1B2013-57) for financial support. M.T.-S. thanks the Ministry of Science and Innovation of Spain for a Ph.D. fellowship (FPU program). We are grateful to ISIS for the award of beamtime on SANS2D (Reference RB 122066), and we thank Richard Heenan for assistance on the beamline. |
| Databáze: | OpenAIRE |
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