Conformational Effects on the Electron-Transfer Efficiency in Peptide Foldamers Based on α,α-Disubstituted Glycyl Residues

✍ Scribed by Emanuela Gatto; Alessandro Porchetta; Lorenzo Stella; Ivan Guryanov; Fernando Formaggio; Claudio Toniolo; Bernard Kaptein; Quirinus B. Broxterman; Mariano Venanzi

• Book ID: 101775389
• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 281 KB
• Volume: 5
• Category: Article
• ISSN: 1612-1872
• DOI: 10.1002/cbdv.200890113

✦ Synopsis

Abstract

Peptide foldamers based on α,α‐disubstituted glycyl residues were synthesized and chemically characterized to investigate the effects of the electric field generated by a 3~10~‐helix on the rate of intramolecular photoinduced electron‐transfer reactions. To this end, two new octapeptides having identical sequences were suitably side‐chain functionalized with the same electron‐transfer donor–acceptor pair, but inverting the position of the pair along the main chain. The electron‐transfer rate constants, measured by time‐resolved spectroscopy techniques (nanosecond transient absorption and time‐resolved fluorescence), indicated that, in the case of the 3~10~‐helix, the electrostatic effect is significant, but smaller than that obtained for α‐helical peptides. This finding can be likely ascribed to the distortion of the H‐bond network with respect to the helical axis taking place in the former secondary structure. Overall, these results could have implications on electron‐transfer phenomena in model and biomembranes facilitated by peptaibiotics.