Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
J Magn Reson. 2011 Oct;212(2):431-9. doi: 10.1016/j.jmr.2011.08.019. Epub 2011 Aug 17.
A solid-state rotational-echo double resonance (REDOR) NMR method was introduced to identify the ϕ- and ψ-torsion angle from a (1)H-(15)N or (1)H-(13)C' spin system of alanine-like residues in a selectively, uniformly, or extensively (15)N-/(13)C-labeled peptide. When a C(α)(i) or a (15)N peak is site-specifically obtainable in the NMR spectrum of a uniformly (15)N/(13)C-labeled sample system, the ψ- or ϕ-torsion angle specified by the conformational structure of peptide geometry involving (15)N(i)-(1)H(α)i-(15)N(i+1) or (13)C'(i-1)-(1)H(N)i-(13)C'(i) spin system can be identified based on (13)C(α)- or (15)N-detected (1)H(α)-(15)N or (1)H(N)-(13)C REDOR experiment. This method will conveniently be utilized to identify major secondary motifs, such as α-helix, β-sheet, and β-turn, from a uniformly (15)N-/(13)C-labled peptide sample system. When tested on a (13)C-/(15)N-labeled model system of a three amino acid peptide Gly-[U-(13)C, (15)N]Ala-[U-(13)C, (15)N]Leu, the ψ-angle of alanine obtained experimentally, ψ = -40 ± 30°, agreed reasonably well with the X-ray determined angle, ψ = -39°.
介绍了一种固态旋转回波双共振（REDOR）NMR 方法，用于从选择性、均匀性或广泛（15）N/（13）C 标记的肽中丙氨酸样残基的（1）H-（15）N 或（1）H-（13）C'自旋系统中鉴定ϕ-和ψ-扭转角。当在均匀（15）N/（13）C 标记的样品系统的 NMR 光谱中可特异性获得 Cα（i）或（15）N 峰时，涉及（15）N（i）-（1）H（α）i-（15）N（i+1）或（13）C'（i-1）-（1）H（N）i-（13）C'（i）自旋系统的肽几何结构所指定的ψ-或ϕ-扭转角可以基于（13）Cα-或（15）N 检测（1）H（α）-（15）N 或（1）H（N）-（13）C REDOR 实验来鉴定。该方法将方便地用于从均匀（15）N/（13）C 标记的肽样品系统中鉴定主要的二级结构模体，如α-螺旋、β-折叠和β-转角。在对三氨基酸肽 Gly-[U-（13）C，（15）N]Ala-[U-（13）C，（15）N]Leu 的（13）C/（15）N 标记模型系统进行测试时，实验获得的丙氨酸的ψ-角，ψ=-40±30°，与 X 射线确定的角度ψ=-39°相当吻合。
