Supramolecular Systems Chemistry Using Peptides PDF Download

Author: Charalampos Pappas
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ISBN:
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Languages : en
Pages : 464

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Book Description
Responsiveness, functionality and adaptability are further demonstrated using different stimuli. Biocatalytic self-assembly has been utilised to direct supramolecular systems. Thermodynamically driven biocatalytic self-assembly is used to achieve morphological control (fibres, sheets and tubes) on aromatic dipeptide amphiphiles, via minimal stereo-electronic substitution on the para position of the phenylalaline amino acid residue. The control of the resultant supramolecular nanostructures and properties arises from the relative importance of stacking interactions among the aromatics and H-bonding between the dipeptide backbones. The concept of thermodynamically driven biocatalytic self-assembly is further utilised to direct the formation of Dynamic Peptide Libraries (DPLs). The amino acids within a dipeptide sequence are exchanged dynamically using in situ catalytic synthesis and hydrolysis of amide bonds, where the free energy involved in selfassembly of the nanostructure provides the driving force for its formation. The use of searchable dynamic peptide libraries gives rise to the ability to explore the structural sequences space of short peptides. Selective catalytic amplification is achieved through an interplay with environmental triggers. Differential formation of peptide subunits (library members), accompanied with structural reconfiguration is favored in the presence of different environment, such as solvents and salts. Additionally, a direct comparison between biocatalytically driven formation of different molecular species and chemically synthesized assemblies is used to show that shape control may be achieved. Biocatalytic self-assembly is also used to trigger the formation of non-equilibrium transient supramolecular systems. In this case, structural adaption is achieved based on biocatalytic formation and hydrolysis of self-assembling tripeptides, which catalyzed by chymotrypsin, starting from a simple dipeptide methyl ester, the wellknown sweetener, aspartame. The chemical design dictates the kinetics and the consequent lifetime of the nanostructures formed, which can be refueled several times by the addition of the fuel (aspartame), where the fibres are continuously forming and shortening, indicating a dynamically unstable system. This thesis ends with a small chapter, where we demonstrate the use of audible sound frequencies (