A Spirocyclohexyl Nitroxide Amino Acid Spin Label for Pulsed EPR Distance Measurements

Authors

Andrzej Rajca, University of Nebraska - LincolnFollow
Velavan Kathirvelu, University of Denver
Sandip K. Riy, University of Nebraska-Lincoln
Maren Pink, Indiana University
Suchada Rajca, University of Nebraska-LincolnFollow
Santanu Sarkar, University of Nebraska-Lincoln
Sandra S. Eaton, University of Denver
Gareth R. Eaton, University of Denver

Date of this Version

2010

Citation

Chemistry. 2010 May 17; 16(19): 5778–5782.

Comments

Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Used by permission.

Abstract

Site-directed spin labeling (SDSL) and electron paramagnetic resonance (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) (Fmoc) derivative, has been synthesized that exhibit slow enough spin echo dephasing to permit accurate distance measurements by pulse EPR 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 to the study of structure and conformation for peptides and proteins.