Conformational effects on the electron-transfer efficiency in peptide foldamers based on alpha,alpha-disubstituted glycyl residues.
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.
Gatto
Emanuela
E
Department of Chemical Sciences and Technologies, University of Rome 'Tor Vergata', I-00133 Rome.
Porchetta
Alessandro
A
Stella
Lorenzo
L
Guryanov
Ivan
I
Formaggio
Fernando
F
Toniolo
Claudio
C
Kaptein
Bernard
B
Broxterman
Quirinus B
QB
Venanzi
Mariano
M
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
D000621:Aminoisobutyric Acids; D009842:Oligopeptides; D054848:Peptaibols; C104340:2-methylnorvaline; D014633:Valine; D005998:Glycine