First, to assess the differences in the peptides' structures and aggregation in water, we assessed the solvent accessibility for H N atoms of the backbone and the effects of the size of the peptide oligomers or aggregates on the 1 H-NMR line shapes. We utilized a combination of Further analysis of the exchange cross-peaks between backbone H N protons and water in 2D spectra showed that in peptide p1 at concentrations above 0.3 mM, only the sidechain H N of all Arg residues were solvent-accessible. All backbone H N groups were shielded and showed no interaction with water, potentially due to oligomerization or aggregation (Figure ). At a concentration of 0.15 mM, unlike higher concentrations, all backbone H N groups in peptide p1 exhibited exchange cross-peaks with the water signal in the TOCSY and NOESY spectra, confirming their solvent exposure (Figure ). Thus, we can estimate that strong oligomerization of peptide p1 in water occurs at a concentration of 0.15-0.30 mM.