It is widely understood that water molecule plays an inevitable role in modulating structure and stability of biomolecules. Generally, water molecule presented at the vicinity of biomolecules is essential to control the dynamic behavior of biomolecules and their interactions. Nature employs various ions or organic small molecules as a cosolvent to stabilize the biomolecules from harsh environments. It was reported that cosolvent effect on biomolecule’s stability results from the relative partitioning of cosolvent between bulk water and biomolecule-water interface. However, molecular level mechanism by which cosolvent stabilize the biomolecule is remains unknown. In this study, we chose peptide assembly process as a tool to study the molecular level interactions between peptide and solvent molecules. We examined molecular assemblies composed of an amphiphilic polypeptide S30L12 having hydrophilic polysarcosine (PSar) units and α-helical hydrophobic segments made of repeating units of leucine (Leu) and aminoisobutyric acid (Aib) under aqueous conditions (Figure 1). The self-assembly of S25L12 was performed in 1-30 % EtOH/H<sub>2</sub>O mixtures at varying temperatures conditions. Morphology formed by S25L12 helical peptide assembly were observed by TEM analysis over 1 week period. CD measurement was performed to understand S25L12 secondary structure. The membrane fluidity of peptide assembly in 1-30 % EtOH/H<sub>2</sub>O mixtures at varying temperatures was also analyzed by fluorescence polarization method with DPH probe. The morphology of S25L12 assembly revealed that the increasing temperature of S25L12/cosolvent/water mixtures decreased hydrophobic interactions among the peptide and peptide assembly, which was further confirmed by membrane fluidity analysis.

Temperature dependent solvent effects on the self-assembly of amphiphilic helical polypeptide

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.