Structure-Free Validation of Residual Dipolar Coupling and Paramagnetic Relaxation Enhancement Measurements of Disordered Proteins

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• 作者：Francisco N. Newby ; Alfonso De Simone ; Maho Yagi-Utsumi ; Xavier Salvatella ; Christopher M. Dobson ; Michele Vendruscolo
• 刊名：Biochemistry
• 出版年：2015
• 出版时间：November 24, 2015
• 年：2015
• 卷：54
• 期：46
• 页码：6876-6886
• 全文大小：549K
• ISSN：1520-4995

文摘

Residual dipolar couplings (RDCs) and paramagnetic relaxation enhancements (PREs) have emerged as valuable parameters for defining the structures and dynamics of disordered proteins by nuclear magnetic resonance (NMR) spectroscopy. Procedures for their measurement, however, may lead to conformational perturbations because of the presence of the alignment media necessary for recording RDCs, or of the paramagnetic groups that must be introduced for measuring PREs. We discuss here experimental methods for quantifying these effects by considering the case of the 40-residue isoform of the amyloid 尾 peptide (A尾40), which is associated with Alzheimer鈥檚 disease. By conducting RDC measurements over a range of concentrations of certain alignment media, we show that perturbations arising from transient binding of A尾40 can be characterized, allowing appropriate corrections to be made. In addition, by using NMR experiments sensitive to long-range interactions, we show that it is possible to identify relatively nonperturbing sites for attaching nitroxide radicals for PRE measurements. Thus, minimizing the conformational perturbations introduced by RDC and PRE measurements should facilitate their use for the rigorous determination of the conformational properties of disordered proteins.