Covalent Catalysis by a Photoresponsive Small Molecule Esterase Mimic

Kashyap, Prajakta (2025) Covalent Catalysis by a Photoresponsive Small Molecule Esterase Mimic. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS Dissertation of Prajakta Kashyap (20MS120)) 20MS120_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (3MB)

Abstract

The development of enzyme mimics that combine catalytic efficiency with external control is a compelling challenge in the field of biomimetic chemistry. In this thesis we try to design and synthesise a photoresponsive enzyme mimic capable of covalent catalysis of ester hydrolysis, wherein the catalytic activity can be modulated by light through a reversible structural change. Inspired by the active sites of natural enzymes where residues in proximity, such as lysine and histidine in protein environments, work in conjugation to carry out various catalytic functions, we have developed a synthetic construct (synzyme) in which these functionalities are connected via an azobenzene photoswitch. The underlying mechanism mimics natural covalent catalysis, wherein a primary amine forms a transient imine bond with the substrate, while the imidazole assists in hydrolysis via a general acid–base catalysis type of pathway. By incorporating a photoswitch into this design, we can enable the system to toggle between “on” and “off” states without the need for any chemical reagents, allowing for clean, waste-free, sustainable and externally regulated activation. The strategy builds on prior peptide-based catalytic architectures and demonstrates how azobenzene-based dynamic systems can be incorporated to construct efficient and controllable enzyme mimics.

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