Influence of central sidechain on self-assembly of glycine-x-glycine peptides

• Published in: Soft matter Vol. 19; no. 3; pp. 394 - 49
• Main Authors: Thursch, Lavenia J, Lima, Thamires A, O'Neill, Nichole, Ferreira, Fabio F, Schweitzer-Stenner, Reinhard, Alvarez, Nicolas J
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 18.01.2023
• Subjects: Biomedical engineering; Chemical properties; Ethanol; Fibrillogenesis; Glycine; Greenhouse gases; Hydrogen bonding; Hydrophobicity; Low molecular weights; Microscopy; Molecular weight; Peptides; Peptides - chemistry; pH effects; Residues; Rheological properties; Rheology; Self-assembly; Spectroscopy; Stacking; Uniqueness; Water - chemistry; X-ray diffraction
• ISSN: 1744-683X; 1744-6848
• DOI: 10.1039/d2sm01082h

Low molecular weight gelators (LMWGs) are the subject of intense research for a range of biomedical and engineering applications. Peptides are a special class of LMWG, which offer infinite sequence possibilities and, therefore, engineered properties. This work examines the propensity of the GxG peptide family, where x denotes a guest residue, to self-assemble into fibril networks via changes in pH and ethanol concentration. These triggers for gelation are motivated by recent work on GHG and GAG, which unexpectedly self-assemble into centimeter long fibril networks with unique rheological properties. The propensity of GxG peptides to self-assemble, and the physical and chemical properties of the self-assembled structures are characterized by microscopy, spectroscopy, rheology, and X-ray diffraction. Interestingly, we show that the number, length, size, and morphology of the crystalline self-assembled aggregates depend significantly on the x-residue chemistry and the solution conditions, i.e. pH, temperature, peptide concentration, etc. The different x-residues allow us to probe the importance of different peptide interactions, e.g. π-π stacking, hydrogen bonding, and hydrophobicity, on the formation of fibrils. We conclude that fibril formation requires π-π stacking interactions in pure water, while hydrogen bonding can form fibrils in the presence of ethanol-water solutions. These results validate and support theoretical arguments on the propensity for self-assembly and leads to a better understanding of the relationship between peptide chemistry and fibril self-assembly. Overall, GxG peptides constitute a unique family of peptides, whose characterization will aid in advancing our understanding of self-assembly driving forces for fibril formation in peptide systems. Low molecular weight gelators (LMWGs) are the subject of intense research for a range of biomedical and engineering applications.