Fig. 2: Characterization of SP-A derived peptide assemblies.
From: Exploration of the hierarchical assembly space of collagen-like peptides beyond the triple helix
a Amino acid sequences of SP-A derived collagen-like peptides SPA-bcb, SPA-Rat, and SPA-Human. Grey highlighted the non-collagen-like domain, and yellow highlighted the alanine residue, which is cysteine in the native pulmonary surfactant protein-A. Yellow highlights Cys6 to Ala substitution. Numbering starts after the signal sequence. b CD spectra of the folded triple helices. Black: SPA-Rat, green: SPA-human, red: SPA-bcb. c Thermal stability study of the assemblies. Signals were monitored at 224 nm. *SPA-bcb peptides formed a heterogeneous assembly that contains precipitate. d The first-order derivatives of the melting curves presented in (c). See “Methods” for CD conditions. e Size exclusion chromatography of SPA-Rat (black), SPA-Human(green), and C1q 18-mer(orange). Source data for CD and SEC are provided as a Source Data file. f Representative cryo-EM image of SPA-Human peptide assembly. The scale bar is 20 nm. The red arrow highlights the hollow protein nanoparticles. g 2D class averaging processing of the cryo-EM images of SPA-Human peptide assembly. h Low-resolution density map of SPA-Human peptide oligomeric assembly.
