title: Parametrization, molecular dynamics simulation, and calculation of electron spin resonance spectra of a nitroxide spin label on a polyalanine alpha-helix.
abstract: The nitroxide spin label 1-oxyl-2,2,5,5-tetramethylpyrroline-3-methyl-methanethiosulfonate (MTSSL), commonly used in site-directed spin labeling of proteins, is studied with molecular dynamics (MD) simulations. After developing force field parameters for the nitroxide moiety and the spin label linker, we simulate MTSSL attached to a polyalanine alpha-helix in explicit solvent to elucidate the factors affecting its conformational dynamics. Electron spin resonance spectra at 9 and 250 GHz are simulated in the time domain using the MD trajectories and including global rotational diffusion appropriate for the tumbling of T4 Lysozyme in solution. Analysis of the MD simulations reveals the presence of significant hydrophobic interactions of the spin label with the alanine side chains.
authors.affiliation: Department of Physics, Cornell University, Ithaca, New York 14853, USA.
authors.forename: Deniz
authors.initials: D
authors.lastname: Sezer
authors.forename: Jack H
authors.initials: JH
authors.lastname: Freed
authors.forename: Benoît
authors.initials: B
authors.lastname: Roux
mesh_terms: D003198:Computer Simulation; D003432:Cross-Linking Reagents / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008968:Molecular Conformation; D009589:Nitrogen Oxides / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary; D013113:Spin Labels
chemical_list: D003432:Cross-Linking Reagents; D009589:Nitrogen Oxides; D010455:Peptides; D013113:Spin Labels; C019529:polyalanine