Solution PRE NMR

Theory and Applications of Nitroxide-based Paramagnetic Cosolutes for Probing Intermolecular and Electrostatic Interactions on Protein Surfaces

“…R b was set to R C + 2 Å for all simulations in this study. The Force-Free Hard-Sphere model (FFHS) 54,55 corresponds to eq 31 with α = 1. where the ionic strength is defined as = I n Z (1/2) j j j 2 , and the (35) where (36) if the short-range interaction is placed between the O atom of the nitroxide moiety of the cosolute and the nucleus of interest; and…”

“…Paramagnetic metal ions have also been used as contrast reagents in magnetic resonance imaging (MRI), and the development of theoretical and experimental methods for the analysis of the sPRE in the context of MRI has been the subject of extensive investigation. − Although nitroxide free radicals, such as hydroxy-TEMPO (4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl), have been widely used in the past to study protein solvent accessibility, − their intrinsic hydrophobicity makes quantitative interpretation difficult, as they tend to bind preferentially to hydrophobic regions on the protein surface. For this reason, less hydrophobic, chelated metal ion complexes, such as gadolinium-diethylenetriamine pentaacetic acid-bismethylamide, are better suited for characterizing protein solvent exposure and for protein structure refinement. ,, Recently, nitroxide-based paramagnetic solutes have been employed as polarizing agents in liquid state dynamic nuclear polarization. − …”

“…For this reason, less hydrophobic, chelated metal ion complexes, such as gadolinium-diethylenetriamine pentaacetic acid-bismethylamide, are better suited for charac-terizing protein solvent exposure and for protein structure refinement. 12,19,35 Recently, nitroxide-based paramagnetic solutes have been employed as polarizing agents in liquid state dynamic nuclear polarization. 36−39 Previously, we showed that nitroxide-based cosolutes can be used to provide quantitative measures of the energetics and dynamics of cosolute−protein interactions at atomic resolution through two parameters obtained by simultaneously fitting the transverse sPRE (Γ 2 ) at one spectrometer field and the longitudinal sPRE (Γ 1 ) at multiple spectrometer fields to an ansatz spectral density function comprising a concentrationnormalized equilibrium average of the interspin separation, ⟨r −6 ⟩ norm , and an effective correlation time τ C for the electron− proton vector.…”

Membrane surface recognition by the ASAP1 PH domain and consequences for interactions with the small GTPase Arf1

“…Second, methyl PREs were obtained in the presence of a soluble paramagnetic probe, a method referred to as co-solute or solvent PRE (sPRE) (21) that reports on the solvent accessibility of an atom. Figure 3C compares the sPRE rates measured for ASAP1-PH free in solution and bound to NDs [PC:PI(4,5)P 2 , 95:5], and the results are mapped onto the ASAP1-PH domain structure.…”

A Platform of Phenol‐Based Nitroxide Radicals as an “EPR Toolbox” in Supramolecular and Click Chemistry

“…Spin probing and spin labeling of supramolecular systems are well established methods in applied magnetic resonance (MR) techniques such as electron paramagnetic resonance (EPR) and in some nuclear magnetic resonance (NMR) methods (e. g. DNP-NMR, PRE-NMR). [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Starting more than 50 years ago with the work of Lebedev et al (1960) and Neiman et al (1964), [17,18] nitroxide radicals, especially the tetramethylpiperidine-N-oxyl radical, TEMPO, are well-studied compounds with a wide range of applications, e. g. in biophysics, modern physical and advanced organic/pharmaceutical chemistry, polymer science, molecular biology and medicine. [1,[19][20][21][22][23][24][25][26][27][28][29] It should be noted that probably the first relatively stable nitroxide radical, the potassium salt of nitrosodisulfonate, was synthesized by pivotal 19 th century chemist Edmond Frémy and is still often called "Frémy's salt".…”