Imaging Protein Fibers at the Nanoscale and In Situ

Coiled-coil scallops (Chlamys farreri) peptide hydrogel with metal ionic and temperature tunable assembly

Self-assembly of peptides is a powerful method of preparing nanostructured materials. Peptides frequently utilize charged groups as a convenient switch for controlling assembly state by pH, ionic strength or temperature. In this study, the molecular properties and gel-forming ability of Chlamys farreri protein hydrolysates were studied. According to self-assembled theory, the presence of isoleucine at position 'a' and leucine at 'd' causes a switch between coiled-coil structures. Compared to P-2-CG, the components of α-helix (23.60 ± 0.56%) were changed into β-sheet (4.83 ± 2.86%) in the secondary structure of the hydrogel induced by ZnCl2. NMR siginals appeared at high field,which indicated hydrogen bonds were formed between P-2-CG and solvent environments at 20 °C. With temperature going up, the hydrogen bonds were broken and nanofibrils were changed into dense aggregates. We expected that P-2-CG could provide a new candidate for preparing metal-induced nanofibers or hydrogels with further applications in food industry.

Imaging and 3D Reconstruction of De Novo Peptide Capsids

Nanoscale systems encapsulating biomacromolecules hold promise for cell and gene therapies. Common issues hampering progress include polydispersity, heterogeneity in size and shape, agglomeration, and poor stability. Much attention is given to the search of novel designs. However, reliable protocols for the validation of encapsulating systems in the continuum of their physicochemical properties, from design to ultrastructure, are lacking. Herein, we report electron microscopy protocols for biologically functional shell-like peptide capsids, which exhibit the physical characteristics of viruses including folding-mediated self-assembly, hollow shell morphology, and uniformity in size.