title: Conformational effects on the electron-transfer efficiency in peptide foldamers based on alpha,alpha-disubstituted glycyl residues.
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.
authors.affiliation: Department of Chemical Sciences and Technologies, University of Rome 'Tor Vergata', I-00133 Rome.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Gatto
authors.forename: Alessandro
authors.initials: A
authors.lastname: Porchetta
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Stella
authors.forename: Ivan
authors.initials: I
authors.lastname: Guryanov
authors.forename: Fernando
authors.initials: F
authors.lastname: Formaggio
authors.forename: Claudio
authors.initials: C
authors.lastname: Toniolo
authors.forename: Bernard
authors.initials: B
authors.lastname: Kaptein
authors.forename: Quirinus B
authors.initials: QB
authors.lastname: Broxterman
authors.forename: Mariano
authors.initials: M
authors.lastname: Venanzi
mesh_terms: D000621:Aminoisobutyric Acids / Q000737:chemistry; D004579:Electron Transport; D005998:Glycine / Q000031:analogs & derivatives*; D006860:Hydrogen Bonding; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry*; D054848:Peptaibols / Q000737:chemistry; D017433:Protein Structure, Secondary; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D055672:Static Electricity; D014633:Valine / Q000031:analogs & derivatives / Q000737:chemistry
chemical_list: D000621:Aminoisobutyric Acids; D009842:Oligopeptides; D054848:Peptaibols; C104340:2-methylnorvaline; D014633:Valine; D005998:Glycine