Watt Kate, McEwan Iain J
School of Medical Sciences, University of Aberdeen, Aberdeen, Scotland, UK.
Methods Mol Biol. 2009;505:205-18. doi: 10.1007/978-1-60327-575-0_12.
X-ray crystallography and nuclear magnetic resonance (NMR) spectroscopy have proved powerful methods for studying the structure of the isolated ligand and DNA-binding domains of nuclear receptors. However, the N-terminal domain (NTD), which in some members of the superfamily is important for transcriptional regulation, and the full-length receptor proteins have proved more challenging. The NTD of different nuclear receptors show little sequence homology and can vary dramatically in length from a few to several hundred amino acids. Low resolution structural analysis using circular dichroism, NMR, steady-state fluorescence spectroscopy, and Fourier transformed infrared spectroscopy has provided valuable information on the conformation and folding of the structurally plastic NTD. In this chapter, we discuss protocols for measuring the intrinsic fluorescence emission spectrum for tryptophan residues under different experimental conditions of protein folding and unfolding.
X射线晶体学和核磁共振（NMR）光谱已被证明是研究核受体分离的配体和DNA结合结构域结构的强大方法。然而，超家族中的一些成员中对转录调节很重要的N端结构域（NTD）以及全长受体蛋白，已被证明更具挑战性。不同核受体的NTD显示出很少的序列同源性，长度可以从几个氨基酸到几百个氨基酸有很大差异。使用圆二色性、NMR、稳态荧光光谱和傅里叶变换红外光谱进行的低分辨率结构分析，已经提供了关于结构可塑性NTD的构象和折叠的有价值信息。在本章中，我们讨论了在蛋白质折叠和去折叠的不同实验条件下测量色氨酸残基固有荧光发射光谱的方法。
