Functional Supramolecular Architectures Inspired from Biological Systems

Pal, Sumit (2025) Functional Supramolecular Architectures Inspired from Biological Systems. PhD thesis, Indian Institute of Science Education and Research Kolkata.

Text (PhD thesis of Sumit Pal (19RS029)) 19RS029.pdf - Submitted Version Restricted to Repository staff only Download (7MB)

Abstract

The present thesis, “Functional Supramolecular Architectures Inspired from Biological Systems” explores minimal building blocks based non-equilibrium supramolecular assemblies for mimicking diverse biological functions. Minimal peptide sequences have been used to integrate two important features of living systems i.e. metabolism under non-equilibrium conditions. Moreover, minimal systems have been designed which could show compartmentalization far from equilibrium and could manipulate orthogonal catalytic activities, thus creating minimal reaction network. Chapter 1 discusses briefly about the different self-assembly processes associated with different fundamental mechanisms of complex biological systems and recent advancements in terms of synthetic systems. Chapter 2 discusses about substrate driven histidine-based generation of non-equilibrium catalytic microphases which can show emergence of peroxidase activity. The catalytic microphases can augment the catalytic potential of cofactor hemin that degrades the substrate molecules, resulting in disassembly of the catalytic microphases. Further, the histidine-based catalytic microphases show orthogonal hydrolase-mimic which results in the generation of the same substrate required for the creation of the catalytic microphases. Overall, these sets of reactions create a minimal reaction network mimicking protometabolism resulting in the increased lifetime of the catalytic microphases. Chapter 3 demonstrates the generation of substrate driven short peptide-based non-equilibrium self-assemblies. The non-equilibrium catalytic microphases show acceleration of biologically important hydrolase-peroxidase catalytic activity by exploiting covalent catalysis, an advanced trait seen in extant enzymes. Moreover, the importance of co-localization of catalytic (hemin, imidazole and lysine) units required for the accelerated cascade activity is discussed. Chapter 4 presents minimal reaction network driven generation of membraneless liquid droplets from small molecule. The product of the reaction acts as autocatalyst for the generation of the active substrate required for phase separation, thus amplifying the droplet formation. The droplets can concentrate different guest molecules. The kinetics of phase separation can be manipulated in presence of diverse external stimuli. Moreover, the importance of liquid droplets in augmenting the oxidation potential of hemin, cofactor of natural peroxidase is discussed. Chapter 5 features the non-equilibrium generation of membraneless coacervates from minimal synthetic building blocks. The dynamic imine bond between the substrate and catalyst facilitates the formation of coacervates which enhances the catalytic potential of histidine units by bringing them in close proximity. The hydrolysis of substrate by the histidines results in droplet dissolution. Chapter 6 discusses the overall summary of all the works and portrays the significance achieved by these findings. Moreover, a broad overview of the possible future directions has been discussed.

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