Peptide foldamers based on alpha,alpha-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 alpha-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.

Conformational effects on the electron-transfer efficiency in peptide foldamers based on alpha,alpha-disubstituted glycyl residues

GURYANOV, IVAN;FORMAGGIO, FERNANDO;TONIOLO, CLAUDIO;
2008

Abstract

Peptide foldamers based on alpha,alpha-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 alpha-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.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/2438108
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