Cooling overall spin temperature: Protein NMR experiments optimized for longitudinal relaxation effects
Cooling overall spin temperature: Protein NMR experiments optimized for longitudinal relaxation effects
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DOI：
10.1016/j.jmr.2005.09.011
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发表时间：
2006-02-01
影响因子：
2.2
通讯作者：
Campbell, ID
中科院分区：
文献类型：
--
作者：
Deschamps, M;Campbell, ID
在高场下对质子化蛋白质进行的实验中，80%的核磁共振波谱仪时间都花在记录自由感应衰减后等待H - 1原子恢复其极化上。先前已表明，对大分子中一部分质子的选择性激发会使所选质子的纵向弛豫更快[K. 佩尔武申，B. 沃格利，A. 埃列茨基，《TROSY核磁共振波谱中的纵向H - 1弛豫优化》，《美国化学会志》124（2002年）12898 - 12902；P. 尚达，B. 布鲁施克，《用于在秒级时间尺度上实时研究蛋白质动态事件的极快速二维核磁共振波谱》，《美国化学会志》127（2005年）8014 - 8015；H.S. 阿特雷亚，T. 齐佩尔斯基，《用于蛋白质完全共振指认的G - 矩阵傅里叶变换核磁共振波谱》，《美国国家科学院院刊》101（2004年）9642 - 9647]。未被选择的质子库充当“热库”，自旋扩散过程（“翻转 - 翻转”跃迁）将来自受激质子库的多余能量传导至分子中其他弛豫过程可耗散多余能量的区域的未被选择的质子。我们在此介绍一种基于一个选择性E - BURP脉冲的灵敏度增强的HSQC序列（COST - HSQC），它可用于质子化的N - 15富集蛋白质（有或没有C - 13同位素富集）。将该实验与带有水翻转回波脉冲的梯度灵敏度增强的HSQC进行了比较（水翻转回波脉冲抑制H - 1(N)和H - 1(α)自旋之间的自旋扩散）。结果表明该实验在某些情况下具有显著优势。对一些观察到的局限性，即短恢复延迟时的样品过热以及复杂的纵向弛豫行为进行了讨论和分析。（c）2005爱思唯尔公司。保留所有权利。
In experiments performed on protonated proteins at high fields, 80% of the NMR spectrometer time is spent waiting for the H-1 atoms to recover their polarization after recording the free induction decay. Selective excitation of a fraction of the protons in a large molecule has previously been shown to lead to faster longitudinal relaxation for the selected protons [K. Pervushin, B. Vogeli, A. Eletsky, Longitudinal H-1 relaxation optimization in TROSY NMR spectroscopy, J. Am. Chem. Soc. 124 (2002) 12898-12902; P. Schanda, B. Brutscher, Very fast two-dimensional NMR spectroscopy for real-time investigation of dynamic events in proteins on the time scale of seconds, J. Am. Chem. Soc. 127 (2005) 8014-8015; H.S. Attreya, T. Szyperski, G-matrix Fourier transform NMR spectroscopy for complete protein resonance assignment, Proc. Natl. Acad. Sci. USA 101 (2004) 9642-9647]. The pool of non-selected protons acts as a "thermal bath" and spin-diffusion processes ("flip-flop" transitions) channel the excess energy from the excited pool to the non-selected protons in regions of the molecule where other relaxation processes can dissipate the excess energy. We present here a sensitivity enhanced HSQC sequence (COST-HSQC), based on one selective E-BURP pulse, which can be used on protonated N-15 enriched proteins (with or without C-13 isotopic enrichment). This experiment is compared to a gradient sensitivity enhanced HSQC with a water flip-back pulse (the water flip-back pulse quenches the spin diffusion between H-1(N) and H-1(alpha) spins). This experiment is shown to have significant advantages in some circumstances. Some observed limitations, namely sample overheating with short recovery delays and complex longitudinal relaxation behaviour are discussed and analysed. (c) 2005 Elsevier Inc. All rights reserved.