Banham J E, Baker C M, Ceola S, Day I J, Grant G H, Groenen E J J, Rodgers C T, Jeschke G, Timmel C R
Centre for Advanced Electron Spin Resonance, University of Oxford, OX1 3QR, UK.
J Magn Reson. 2008 Apr;191(2):202-18. doi: 10.1016/j.jmr.2007.11.023. Epub 2007 Dec 15.
Inter-spin distances between 1 nm and 4.5 nm are measured by continuous wave (CW) and pulsed electron paramagnetic resonance (EPR) methods for a series of nitroxide-spin-labelled peptides. The upper distance limit for measuring dipolar coupling by the broadening of the CW spectrum and the lower distance limit for the present optimally-adjusted double electron electron resonance (DEER) set-up are determined and found to be both around 1.6-1.9 nm. The methods for determining distances and corresponding distributions from CW spectral line broadening are reviewed and further developed. Also, the work shows that a correction factor is required for the analysis of inter-spin distances below approximately 2 nm for DEER measurements and this is calculated using the density matrix formalism.
对于一系列氮氧自旋标记肽，通过连续波（CW）和脉冲电子顺磁共振（EPR）方法测量了1纳米至4.5纳米之间的自旋间距。通过连续波谱展宽测量偶极耦合的上限距离以及当前最佳调整的双电子电子共振（DEER）装置的下限距离被确定，发现两者都在1.6 - 1.9纳米左右。回顾并进一步发展了从连续波谱线展宽确定距离和相应分布的方法。此外，研究表明，对于DEER测量，在分析低于约2纳米的自旋间距时需要一个校正因子，这是使用密度矩阵形式计算得出的。
