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Long‐Range Electron Transfer in Rigid 3 10 ‐Helical Oligopeptides Containing Redox Cyclic a‐Amino Acids
Author(s) -
Lang Kamil,
Kuki Atsuo
Publication year - 1999
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1999.tb08254.x
Subject(s) - chemistry , oligopeptide , steric effects , electron transfer , nanosecond , amino acid , side chain , acceptor , electron acceptor , peptide , residue (chemistry) , electron donor , photoinduced electron transfer , cyclic peptide , amino acid residue , crystallography , stereochemistry , photochemistry , peptide sequence , organic chemistry , laser , biochemistry , physics , optics , catalysis , condensed matter physics , polymer , gene
Intrahelical photoinduced electron transfer processes (ET) in conformationally restricted oligopeptides have been studied by nanosecond time‐resolved transient spectroscopy. The helical peptides were constructed from ste‐rically hindered a‐aminoisobutyric acid (Aib) and two cyclic a‐amino acids (Aib class) bearing electron acceptor and donor side chains (DkNap, ThQx). This helical backbone design provides high conformation stability, as previously demonstrated, and yields reliable 3 10 ‐helical architectures in solution. The forward ET between ThQx and 3 DkNap is followed by a slow back ET thus giving rise to an accumulation of the charge‐separated ion pairs for hundreds of nanoseconds. We demonstrate the modulation of electronic interactions by the number of intervening Aib residues separating acceptor‐donor side chains and propose modifications of the peptide framework by inclusion of a non‐Aib amino acid residue. These well‐defined and sterically stable frameworks are suited for the precise evaluation of intrahelical electron transfer processes mediated by peptides.