Dissertations, Theses, and Capstone Projects

Date of Degree

6-2021

Document Type

Dissertation

Degree Name

Ph.D.

Program

Chemistry

Advisor

Rein V Ulijn

Committee Members

Aneta Mieszawska

Hiroshi Matsui

Keywords

Peptide assembly, fluorescence

Abstract

The structure and machinery of living systems are based on sequence-specific peptides that are composed of just 20 amino acids. The supramolecular assembly of peptides is a result of weak non-covalent forces among the amino acid residues that lead to diverse ordered structures and properties. Rational peptide design with sequence-specific combination of the 20 genes encoded amino acids is a promising new route for the production of materials with new functional properties. Aromatic residues have been shown an important role in self-assembly through increasing the aggregation possibility. They also have shown fluorescence properties in the ultraviolet range. In this thesis I described the development of a design approach based on aqueous self-assembly aggregation propensity (AP) of the aromatic amino acids with the purpose of achieving fluorescence emission properties in the visible spectrum. This is achieved by taking advantage of a combination of electrostatic, π-π and cation-π interactions in a set of peptides that are composed of pairs of aromatic amino acids combined with cationic lysine residues. We found that our self-assembled aromatic tripeptides show fluorescence and absorbance that is significantly shifted compared to that of the individual amino acids. Alteration of the sequence in the peptide design resulted in the sequence-dependent emission and absorbance properties. Our experiments are focused on understanding the reasons of these by integrated experimental and computational studies. This is achieved by studying the effect of the single molecule conformation and supramolecular aggregation on the resulting properties using a range of complementary spectroscopy, microscopy techniques and modelling. In the final chapter, we will discuss the compounds’ potential to be used as expressable fluorescent tags and co-assembly with drug molecules to enable visualization of drug release and, potentially, drug delivery.

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