Supramolecular Order And Interfacial Properties Of Peptides Self-Assemblies

Protein plays an important role in biology to endow versatile functions such as catalysis,trassport,and ion channels.The physiochemical function of proteins arises from correct protein folding into precisely controlled structures,wheras protein misfolding may cause protein malfunctioning or even severe diseases.The structure of protein is vulnerable to interference from environmental stimuli such as p H,solvent,and heating,which can cause protein denaturation and the loss of its function.Understanding the structure-function relationship of proteins,especially enzymes,is of great significance to protein engineering as well as de novo design of proteins to optimise biological activity.Self-assembly of minimalized peptides can be used to mimic the biological function and catalytic activity of proteins,thereby offering an important platform to uncover the relationship between structure and function.In this thesis,a series of peptides amphiphiles with a β-sheet sequence and a catalytic center were designed to investigate the effect of supramolecular structures on the enzyme-like catalytic activity.An unprecedented phenomenon of temperature-dependent phase transition was observed,which was ascribed to the structural evolution from kinetically trapped nanofibrils into nanosheets.We employed a range of characterization methods such as CD spectrum,TEM,AFM,and FRET to indepth research on supramolecular structures,intermolecular force,and molecular dynamics during the collective transformation process.We also studied the effects of ion strength,solution p H and other factors on phase change processes.We discovered a huge difference in catalytic activity of different peptides and highlighted a nonmonotonous correlation of catalytic activity with supramolecular order.Furthermore,the coupling of temperature and p H can be used to achieve reversible regulation and regeneration of peptides nanostructures and their catalysis.The study of this thesis provides the foundation for better understanding of the essence of dynamic biological assembly and protein catalysis.