Identification of protein surfaces by NMR measurements with a pramagnetic Gd(III) chelate. |
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Authors: | Guido Pintacuda Gottfried Otting |
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Affiliation: | Department of Medical Biochemistry and Biophysics, Karolinska Institute, Tomtebodav?gen 6, S-171 77 Stockholm, Sweden. |
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Abstract: | Gd-diethylenetriamine pentaacetic acid-bismethylamide, Gd(DTPA-BMA), is shown to be a reagent suitable for the identification of protein surfaces. Compared to the conventionally used spin-label TEMPOL, Gd(DTPA-BMA) is a stronger relaxation agent, requiring lesser concentrations to achieve the same paramagnetic relaxation enhancement of solvent-exposed protein protons. It is also less hydrophobic and therefore less prone to specific binding to proteins. Relaxation enhancements predicted by a second-sphere interaction model correlated with experimental data recorded with ubiquitin, while the correlation with corresponding data recorded with TEMPOL was poor. |
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