Vibrational study of autoassembling oligopeptides for biomedical applications.

Eight alternating polar/non-polar peptides derived from -sheet EAK-16 were studied for their possible use as biomimetic materials, due to their self-assembling properties. IR and Raman spectroscopies were used to investigate the influence of the sequence on the prevailing conformation of the peptide and its changes after solubilisation in saline phosphate buffer and lyophilisation. As regards the as-synthesised peptides, acidic substitution (Glu Asp, peptide 2), basic substitution (Lys Orn, peptide 3), (Glu Asp and Lys Orn, peptide 4) and spacer substitution (Ala Abu, peptide 5; Ala Tyr, peptide 6) did not induce significant conformational changes with respect to EAK-16 (peptide 1); the prevailing structure was -sheet (about 70%), with about 15% of -turn, 10% of unordered structure and a minor -helix content. The insertion at the N-terminus of the Arg-Gly-Asp sequence (peptide 7), important for cell adhesion, induced a decrease in the -sheet content (50%), while the simultaneous scrambling of the sequence (peptide 8) made -helix the prevailing structure. Solubilisation/lyophilisation procedures generally induced a change towards a less ordered conformation in all the analysed peptides. However, for peptides 1-7, the prevailing conformation remained -sheet. Peptide 8 was prevalently unordered with a lower -sheet content. Copyright © 2007 John Wiley & Sons, Ltd.