title: Measurement of rotational dynamics by the simultaneous nonlinear analysis of optical and EPR data.
abstract: In the preceding companion article in this issue, an optical dye and a nitroxide radical were combined in a new dual function probe, 5-SLE. In this report, it is demonstrated that time-resolved optical anisotropy and electron paramagnetic resonance (EPR) data can be combined in a single analysis to measure rotational dynamics. Rigid-limit and rotational diffusion models for simulating nitroxide EPR data have been incorporated into a general non-linear least-squares procedure based on the Marquardt-Levenberg algorithm. Simultaneous fits to simulated time-resolved fluorescence anisotropy and linear EPR data, together with simultaneous fits to experimental time-resolved phosphorescence anisotropy decays and saturation transfer EPR (ST-EPR) spectra of 5-SLE noncovalently bound to bovine serum albumin (BSA) have been performed. These results demonstrate that data from optical and EPR experiments can be combined and globally fit to a single dynamic model.
authors.affiliation: Vanderbilt University, Nashville, Tennessee 37232.
authors.forename: E J
authors.initials: EJ
authors.lastname: Hustedt
authors.forename: C E
authors.initials: CE
authors.lastname: Cobb
authors.forename: A H
authors.initials: AH
authors.lastname: Beth
authors.forename: J M
authors.initials: JM
authors.lastname: Beechem
mesh_terms: D055592:Biophysical Phenomena; D001703:Biophysics; D003627:Data Interpretation, Statistical; D004058:Diffusion; D004578:Electron Spin Resonance Spectroscopy / Q000706:statistics & numerical data; D004801:Eosine Yellowish-(YS) / Q000031:analogs & derivatives; D005454:Fluorescence Polarization / Q000706:statistics & numerical data; D005456:Fluorescent Dyes; D008956:Models, Chemical; D009038:Motion; D011506:Proteins / Q000737:chemistry*; D012399:Rotation; D012710:Serum Albumin, Bovine / Q000737:chemistry; D013113:Spin Labels
chemical_list: D005456:Fluorescent Dyes; D011506:Proteins; D013113:Spin Labels; D012710:Serum Albumin, Bovine; C080729:5-aminoeosin; D004801:Eosine Yellowish-(YS)