Protein Engineering vol. 16 no. 12 pp. 1125-1130, 2003
© 2003 Oxford University Press
Shift of fibril-forming ability of the designed 
-helical coiled-coil peptides into the physiological pH region
1Institute of Protein Research, Russian Academy of Sciences,142290 Pushchino, Moscow Region, Russia, 2Institute of Biochemistry, University of Lausanne, Ch. des Boveresses 155, CH-1066 Epalinges, Switzerland and 3Centre de Recherches de Biochimie Macromoléculaire, CNRS FRE-2593, 1919 Route de Mende, 34293 Montpellier, Cedex 5, France
4 To whom correspondence should be addressed. e-mail: spot{at}vega.protres.ru
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.
Received July 7, 2003; revised October 27, 2003; accepted October 30, 2003