The influence of a dicationic surfactant on the aggregation process of the IVAGVN peptide derived from the human cystatin C sequence (56-61).

Human cystatin C (hCC) undergoes domain swapping and forms amyloid structures. Steric zipper motifs, which are important for hCC fibrillization, have been identified and studied in our previous work. In the present study, we analysed the influence of the selected dicationic surfactant (a derivative of dodecylimidazolium chloride: 3,3'-[α,ω-(dioxahexane)]bis(1-dodecylimidazolium)dichloride) on the structure of the aggregates formed by one such fragment, a peptide with the sequence IVAGVN, corresponding to residues 56-61 in the full-length protein. Changes in the secondary structure of the peptide induced by the surfactant were studied using circular dichroism (CD) and FTIR, and the aggregates were characterised using microscopic techniques (AFM and TEM) and NMR.