Direct Observation of Millisecond to Second Motions in Proteins by Dipolar CODEX NMR Spectroscopy

详细信息    查看全文

• 作者：Alexey Krushelnitsky ; Eduardo deAzevedo ; Rasmus Linser ; Bernd Reif ; Kay Saalwchter ; Detlef Reichert
• 刊名：Journal of the American Chemical Society
• 出版年：2009
• 出版时间：September 2, 2009
• 年：2009
• 卷：131
• 期：34
• 页码：12097-12099
• 全文大小：182K
• 年卷期：v.131,no.34(September 2, 2009)
• ISSN：1520-5126

文摘

We present a site-resolved study of slow (ms to s) motions in a protein in the solid (microcrystalline) state performed with the use of a modified version of the centerband-only detection of exchange (CODEX) NMR experiment. CODEX was originally based on measuring changes in molecular orientation by means of the chemical shift anisotropy (CSA) tensor, and in our modification, angular reorientations of internuclear vectors are observed. The experiment was applied to the study of slow ¹⁵N−¹H motions of the SH3 domain of chicken α-spectrin. The protein was perdeuterated with partial back-exchange of protons at labile sites. This allowed indirect (proton) detection of ¹⁵N nuclei and thus a significant enhancement of sensitivity. The diluted proton system also made negligible proton-driven spin diffusion between ¹⁵N nuclei, which interferes with the molecular exchange (motion) and hampers the acquisition of dynamic parameters. The experiment has shown that approximately half of the peaks in the 2D ¹⁵N−¹H correlation spectrum exhibit exchange in a different extent. The correlation time of the slow motion for most peaks is 1 to 3 s. This is the first NMR study of the internal dynamics of proteins in the solid state on the millisecond to second time scale with site-specific spectral resolution that provides both time-scale and geometry information about molecular motions.