A Spirocyclohexyl Nitroxide Amino Acid Spin Label for Pulsed EPR Spectroscopy Distance Measurements |
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| Authors: | Andrzej Rajca Prof. Velavan Kathirvelu Dr. Sandip K. Roy Dr. Maren Pink Dr. Suchada Rajca Dr. Santanu Sarkar Sandra S. Eaton Prof. Gareth R. Eaton Prof. |
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| Affiliation: | 1. Department of Chemistry, University of Nebraska, Lincoln, NE 68588‐0304 (USA), Fax: (+1)?402‐472‐9402;2. Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208‐2436 (USA), Fax: (+1)?303‐871‐2254;3. Department of Chemistry, Indiana University, Bloomington, IN 47405‐7102 (USA) |
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| Abstract: | Site‐directed spin labeling and EPR spectroscopy offer accurate, sensitive tools for the characterization of structure and function of macromolecules and their assemblies. A new rigid spin label, spirocyclohexyl nitroxide α‐amino acid and its N‐(9‐fluorenylmethoxycarbonyl) derivative, have been synthesized, which exhibit slow enough spin‐echo dephasing to permit accurate distance measurements by pulsed EPR spectroscopy at temperatures up to 125 K in 1:1 water/glycerol and at higher temperatures in matrices with higher glass transition temperatures. Distance measurements in the liquid nitrogen temperature range are less expensive than those that require liquid helium, which will greatly facilitate applications of pulsed EPR spectroscopy to the study of structure and conformation of peptides and proteins. |
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| Keywords: | EPR spectroscopy radicals spin labels spin relaxation spiro compounds |
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