Polarization transfer by cross-correlated relaxation in solution NMR with very large molecules
Polarization transfer by cross-correlated relaxation in solution NMR with very large molecules
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DOI：
10.1073/pnas.96.9.4918
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发表时间：
1999-04-27
影响因子：
11.1
通讯作者：
Wüthrich, K
中科院分区：
文献类型：
--
作者：
Riek, R;Wider, G;Wüthrich, K
在用于研究溶液中生物大分子的常见多维NMR实验中，通过自旋-自旋耦合的磁化转移[极化转移增强的不敏感核（INEPT）]是脉冲方案的关键要素。对于超过100，000的分子量，转移时间期间的横向弛豫可能成为限制因素。本文提出了一种适用于大分子工作的转移技术--交叉弛豫增强极化转移（CRINEPT），它利用交叉相关弛豫诱导极化转移大大降低了INEPT转移的尺寸限制。通过互相关弛豫的极化转移速率与旋转相关时间成正比，因此它成为具有非常高分子量的溶液NMR的高效转移机制。作为第一个实施方案，设计了[N-15，H-1]-相关实验，其利用偶极-偶极耦合和N-15-H-1-部分的化学位移各向异性之间的互相关，用于CRINEPT和横向弛豫优化光谱（TROSY）。当与基于INEPT的[N-15，H-1]-TROSY相比时，这些实验在4 ℃下对于水溶液中的110，000-Da蛋白质的酰胺基团产生高达3倍的信号增强。CRINEPT为溶液NMR开辟了途径，具有超分子结构，如溶解在胶束或脂质囊泡中的膜蛋白，附着在核酸片段上的蛋白质或寡聚蛋白质。
In common multidimensional NMR experiments for studies of biological macromolecules in solution, magnetization transfers via spin-spin couplings [insensitive nuclei enhanced by polarization transfer (INEPT)] are key elements of the pulse schemes, For molecular weights beyond 100,000, transverse relaxation during the transfer time may become a limiting factor. This paper presents a transfer technique for work with big molecules, cross relaxation-enhanced polarization transfer (CRINEPT), which largely reduces the size limitation of INEPT transfers with the use of cross-correlated relaxation-induced polarization transfer. The rate of polarization transfer by cross-correlated relaxation is proportional to the rotational correlation time, so that it becomes a highly efficient transfer mechanism for solution NMR with very high molecular weights. As a first implementation, [N-15,H-1]-correlation experiments were designed that make use of cross-correlation between dipole-dipole coupling and chemical shift anisotropy of the N-15-H-1-moieties for both CRINEPT and transverse relaxation-optimized spectroscopy (TROSY). When compared with INEPT-based [N-15,H-1]-TROSY, these experiments yielded up to 3-fold signal enhancement for amide groups of a 110,000-Da protein in aqueous solution at 4 degrees C. CRINEPT opens avenues for solution NMR with supramolecular structures such as membrane proteins solubilized in micelles or lipid vesicles, proteins attached to nucleic acid fragments, or oligomeric proteins.