Ruppert Matthias, Creon Anne, Tidow Henning, Huse Nils
Hamburg Advanced Research Centre for Bioorganic Chemistry, Institute for Nanostructure and Solid-State Physics, Department of Physics, and Center for Free-Electron Laser Science, University of Hamburg, Luruper Chaussee 149, D-22761 Hamburg, Germany.
Hamburg Advanced Research Centre for Bioorganic Chemistry, Institute for Biochemistry and Molecular Biology, Department of Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany.
J Phys Chem B. 2022 Jan 20;126(2):368-375. doi: 10.1021/acs.jpcb.1c06775. Epub 2022 Jan 6.
We genetically incorporated the unnatural amino acid p-azido-phenylalanine (AzF) into the ubiquitous Ca sensor protein calmodulin (CaM) in complex with different peptides to explore the response of the azido stretching line shape to varying binding motifs with femtosecond infrared spectroscopy. The dynamic response of the azido stretching mode varies in different CaM-peptide complexes. We model these dynamics as coherent excitations of Fermi resonances and extract a lifetime of the azido stretching vibration of about 1 ps. The resulting model parameters are commensurate with the linear infrared absorption lineshapes which suggests that the conformation-sensitive vibrational lineshape could be composed of Fermi resonances that differ between the protein-peptide complexes.
