Hemme Colin A, Warmuth Owen A, Wang Songlin, Williams Christopher G, Thome Alexander, Mueller Leonard J, Rienstra Chad M, Grant Timothy
bioRxiv. 2025 May 6:2025.05.05.652277. doi: 10.1101/2025.05.05.652277.
With recent advances in magic-angle spinning (MAS) solid-state NMR (SSNMR) resolution, precise spectral alignment has become a critical bottleneck in data processing workflows. While solution NMR employs deuterium lock systems, most SSNMR probes still lack this capability; though a lock corrects for magnet drift and instabilities, it is not alone sufficient to account for field gradients, sample temperature differences, and pulse sequence effects that can contribute to referencing errors among several data sets. These offsets become particularly problematic in the lengthy multidimensional experiments that provide the foundation for resonance assignment and structure determination procedures. Currently, researchers rely on manual alignment through visual peak inspection-a qualitative approach that often overemphasizes prominent, outlying peaks while overlooking subtle, global patterns. This subjective process becomes increasingly impractical for use cases with lower sensitivity, such as large proteins with thousands of peaks. To address these challenges, here we present Automated NMR Spectral Alignment ( ), a program that adapts cryo-electron microscopy motion correction principles to NMR spectroscopy. treats NMR spectra as images and applies cross-correlation functions to determine optimal alignment, improving cross-correlation scores from 0.33 to 1.00 in controlled tests and achieving 0.96 correlation in real-world applications with previously misaligned spectra. The algorithm successfully aligns spectra across varying experimental conditions, corrects shifts in long-duration experiments, and works with 2D and 3D datasets, with approaches that can be readily extended to additional dimensions. By eliminating human bias and providing objective, consistent spectral alignment, enhances scientific rigor, improves reproducibility between experiments, and enables automation of critical data processing steps. The software is freely available as an open-source tool, ready for integration into existing NMR workflows.
随着魔角旋转（MAS）固态核磁共振（SSNMR）分辨率的最新进展，精确的谱图对齐已成为数据处理工作流程中的关键瓶颈。虽然溶液核磁共振采用氘锁定系统，但大多数SSNMR探头仍缺乏此功能；尽管锁定可校正磁场漂移和不稳定性，但仅靠它不足以解释可能导致多个数据集之间参考误差的场梯度、样品温度差异和脉冲序列效应。在为共振归属和结构确定程序提供基础的冗长多维实验中，这些偏移尤其成问题。目前，研究人员依靠通过目视检查峰来进行手动对齐——这是一种定性方法，往往过度强调突出的、偏远的峰，而忽略了细微的全局模式。对于灵敏度较低的用例，如具有数千个峰的大蛋白质，这种主观过程变得越来越不实用。为应对这些挑战，我们在此展示自动核磁共振谱图对齐（ ）程序，该程序将冷冻电子显微镜运动校正原理应用于核磁共振光谱学。 将核磁共振谱图视为图像，并应用互相关函数来确定最佳对齐，在对照测试中将互相关分数从0.33提高到1.00，并在实际应用中对先前未对齐的谱图实现了0.96的相关性。该算法成功地在不同实验条件下对齐谱图，校正长时间实验中的偏移，并适用于二维和三维数据集，其方法可轻松扩展到更多维度。通过消除人为偏差并提供客观、一致的谱图对齐， 提高了科学严谨性，改善了实验之间的可重复性，并实现了关键数据处理步骤的自动化。该软件作为开源工具免费提供，可随时集成到现有的核磁共振工作流程中。
