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Semi‐Rigid Nitroxide Spin Label for Long‐Range EPR Distance Measurements of Lipid Bilayer Embedded β‐Peptides
Author(s) -
Wegner Janine,
Valora Gabriele,
Halbmair Karin,
Kehl Annemarie,
Worbs Brigitte,
Bennati Marina,
Diederichsen Ulf
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201805880
Subject(s) - electron paramagnetic resonance , spin label , nitroxide mediated radical polymerization , site directed spin labeling , lipid bilayer , bilayer , peptide , chemistry , transmembrane domain , helix (gastropod) , transmembrane protein , pulsed epr , amino acid , crystallography , spectroscopy , biophysics , nuclear magnetic resonance , membrane , physics , biochemistry , spin echo , magnetic resonance imaging , organic chemistry , snail , ecology , receptor , biology , polymer , radical polymerization , quantum mechanics , radiology , medicine , copolymer
β‐Peptides are an interesting new class of transmembrane model peptides based on their conformationally stable and well‐defined secondary structures. Herein, we present the synthesis of the paramagnetic β‐amino acid β 3 ‐hTOPP (4‐(3,3,5,5‐tetramethyl‐2,6‐dioxo‐4‐oxylpiperazin‐1‐yl)‐ d ‐β 3 ‐homophenylglycine) that enables investigations of β‐peptides by EPR spectroscopy. This amino acid adds to the, to date, sparse number of β‐peptide spin labels. Its performance was evaluated by investigating the helical turn of a 3 14 ‐helical transmembrane model β‐peptide. Nanometer distances between two incorporated β 3 ‐hTOPP labels in different environments were measured by using pulsed electron/electron double resonance (PELDOR/DEER) spectroscopy. Due to the semi‐rigid conformational design, the label delivers reliable distances and sharp (one‐peak) distance distributions even in the lipid bilayer. The results indicate that the investigated β‐peptide folds into a 3.25 14 helix and maintains this conformation in the lipid bilayer.