Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200, København N, Denmark.
J Biomol NMR. 2011 Feb;49(2):139-49. doi: 10.1007/s10858-011-9472-x. Epub 2011 Jan 15.
Secondary chemical shift analysis is the main NMR method for detection of transiently formed secondary structure in intrinsically disordered proteins. The quality of the secondary chemical shifts is dependent on an appropriate choice of random coil chemical shifts. We report random coil chemical shifts and sequence correction factors determined for a GGXGG peptide series following the approach of Schwarzinger et al. (J Am Chem Soc 123(13):2970-2978, 2001). The chemical shifts are determined at neutral pH in order to match the conditions of most studies of intrinsically disordered proteins. Temperature has a non-negligible effect on the (13)C random coil chemical shifts, so temperature coefficients are reported for the random coil chemical shifts to allow extrapolation to other temperatures. The pH dependence of the histidine random coil chemical shifts is investigated in a titration series, which allows the accurate random coil chemical shifts to be obtained at any pH. By correcting the random coil chemical shifts for the effects of temperature and pH, systematic biases of the secondary chemical shifts are minimized, which will improve the reliability of detection of transient secondary structure in disordered proteins.
二级化学位移分析是检测无规卷曲蛋白质中瞬态二级结构的主要 NMR 方法。二级化学位移的质量取决于对随机卷曲化学位移的适当选择。我们报告了 Schwarzinger 等人提出的 GGXGG 肽系列的随机卷曲化学位移和序列校正因子（J Am Chem Soc 123(13):2970-2978, 2001）。这些化学位移是在中性 pH 下确定的，以匹配大多数无规卷曲蛋白质研究的条件。温度对（13）C 随机卷曲化学位移有不可忽略的影响，因此报告了随机卷曲化学位移的温度系数，以允许外推到其他温度。在一系列滴定中研究了组氨酸随机卷曲化学位移的 pH 依赖性，这允许在任何 pH 值下获得准确的随机卷曲化学位移。通过对温度和 pH 的影响校正随机卷曲化学位移，可以最小化二级化学位移的系统偏差，从而提高在无序蛋白质中检测瞬态二级结构的可靠性。
