Shift of fibril-forming ability of the designed  -helical coiled-coil peptides into the physiological pH region

• Published in: Protein engineering, design and selection design and selection, 2003-12, Vol.16 (12), p.1125-1130
• Main Authors: Melnik, T.N., Villard, V., Vasiliev, V., Corradin, G., Kajava, A.V., Potekhin, S.A.
• Format: Article
• Language: English
• ISSN: 1741-0126; 1741-0134
• DOI: 10.1093/protein/gzg138

Recently, we designed a short ±-helical fibril-forming peptide (±FFP) that can form ±-helical nanofibrils at acid pH. The non-physiological conditions of the fibril formation hamper biomedical application of ±FFP. It was hypothesized that electrostatic repulsion between glutamic acid residues present at positions (g) of the ±FFP coiled-coil sequence prevent the fibrillogenesis at neutral pH, while their protonation below pH 5.5 triggers axial growth of the fibril. To test this hypothesis, we synthesized ±FFPs where all glutamic acid residues were substituted by glutamines or serines. The electron microscopy study confirmed that the modified ±FFPs form nanofibrils in a wider range of pH (2.5-11). Circular dichroism spectroscopy, sedimentation, diffusion and differential scanning calorimetry showed that the fibrils are ±-helical and have elongated and highly stable cooperative tertiary structures. This work leads to a better understanding of interactions that control the fibrillogenesis of the ±FFPs and opens opportunities for their biomedical application.