Pulse EPR Measurements of Intramolecular Distances in a TOPP-Labeled Transmembrane Peptide in Lipids.
We present the performance of nanometer-range pulse electron paramagnetic resonance distance measurements (pulsed electron-electron double resonance/double electron-electron resonance, PELDOR/DEER) on a transmembrane WALP24 peptide labeled with the semirigid unnatural amino acid 4-(3,3,5,5-tetra-methyl-2,6-dioxo-4-oxylpiperazin-1-yl)-l-phenylglycine (TOPP). Distances reported by the TOPP label are compared to the ones reported by the more standard MTSSL spin label, commonly employed in protein studies. Using high-power pulse electron paramagnetic resonance spectroscopy at Q-band frequencies (34 GHz), we show that in contrast to MTSSL, our label reports one-peak, sharp (Δr ≤ 0.4 nm) intramolecular distances. Orientational selectivity is not observed. When spin-labeled WALP24 was inserted in two representative lipid bilayers with different bilayer thickness, i.e., DMPC and POPC, the intramolecular distance reported by TOPP did not change with the bilayer environment. In contrast, the distance measured with MTSSL was strongly affected by the hydrophobic thickness of the lipid. The results demonstrate that the TOPP label is well suited to study the intrinsic structure of peptides immersed in lipids.
Electron Spin Resonance Spectroscopy, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
Karin
K
Halbmair
Institute for Organic and Biomolecular Chemistry, Georg-August-University, Göttingen, Germany.
Janine
J
Wegner
Institute for Organic and Biomolecular Chemistry, Georg-August-University, Göttingen, Germany.
Ulf
U
Diederichsen
Electron Spin Resonance Spectroscopy, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany; Institute for Organic and Biomolecular Chemistry, Georg-August-University, Göttingen, Germany. Electronic address: marina.bennati@mpibpc.mpg.de.
Marina
M
Bennati
D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000737:chemistry*; D003497:Cyclic N-Oxides / Q000737:chemistry*; D054659:Diketopiperazines / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D005998:Glycine / Q000031:analogs & derivatives* / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry*; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry*; D000072756:Protein Conformation, alpha-Helical; D013113:Spin Labels
C000621038:4-(3,3,5,5-tetra-methyl-2,6-dioxo-4-oxylpiperazin-1-yl)phenylglycine; D003497:Cyclic N-Oxides; D054659:Diketopiperazines; D008051:Lipid Bilayers; D010455:Peptides; D013113:Spin Labels; C008852:2-phenylglycine; D005998:Glycine