Document Type

Honors Project On-Campus Access Only


Peptides are intriguing catalysts because they occupy a middle ground between enzymes and small-molecule organocatalysts. Although too short to form tertiary and quaternary structures, peptide catalysts can incorporate secondary structures that have potential benefits for catalytic activity. Our group specifically focused on peptides that can form β-hairpins. A β-hairpin is a structural motif of peptides and proteins that contain two antiparallel β-sheets with turn residues at the bend. Peptides that contain β-hairpin structures have been reported to catalyze a variety of organic reactions. We have been interested in the aldol addition reaction between 4-nitrobenzaldehyde and hydroxyacetone catalyzed by a four-residue peptide that has the potential to form a minimal β-hairpin. More specifically, we aimed to test and compare how the initial rates of reaction and stereoselectivity vary based on different catalyst sequences with the same catalytic group (primary amine in the N-terminus) but different i+1 and i+2 turn residues. We used Nuclear Magnetic Resonance Spectroscopy (NMR) to identify peptide secondary structures, determine peptide concentration and record reaction kinetic data under controlled concentrations. We observed significant variation in the initial rates of reactions catalyzed by peptides with different turn residues, indicating the significant role of structure on catalytic activity. Our studies of peptide catalysts may lead to the discovery of design principles that could be used for the development of next generation catalysts.



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