Processing of ND NMR spectra sampled in polar coordinates: a simple Fourier transform instead of a reconstruction
Processing of ND NMR spectra sampled in polar coordinates: a simple Fourier transform instead of a reconstruction
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DOI：
10.1007/s10858-006-9066-1
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发表时间：
2006-09-01
影响因子：
2.7
通讯作者：
Marion, Dominique
中科院分区：
文献类型：
--
作者：
Marion, Dominique
为了减少生物大分子多维NMR谱的采集时间，可以使用投影谱（或者换句话说，在极坐标中采样的谱）。它们的标准处理涉及对投影进行常规 FFT，然后进行重建，即非线性过程。在这次交流中，我们展示了可以在极坐标中实现二维离散傅立叶变换，以直接获得频域频谱。由于局部违反奈奎斯特采样定理而导致的混叠会产生基线脊，但峰值线形状不会像大多数重建方法那样扭曲。采样方案不是线性的，因此时域中的数据点应在极坐标 FT 中进行相应的加权；然而，可以通过对欠采样区域进行额外的数据加权来减少伪影。该处理不需要任何参数调整并且易于使用。为极性采样编写的算法可以适应任何采样方案，并且可以在实验时间和消除伪影方面研究更好的折衷方案。
In order to reduce the acquisition time of multidimensional NMR spectra of biological macromolecules, projected spectra (or in other words, spectra sampled in polar coordinates) can be used. Their standard processing involves a regular FFT of the projections followed by a reconstruction, i.e. a non-linear process. In this communication, we show that a 2D discrete Fourier transform can be implemented in polar coordinates to obtain directly a frequency domain spectrum. Aliasing due to local violations of the Nyquist sampling theorem gives rise to base line ridges but the peak line-shapes are not distorted as in most reconstruction methods. The sampling scheme is not linear and the data points in the time domain should thus be weighted accordingly in the polar FT; however, artifacts can be reduced by additional data weighting of the undersampled regions. This processing does not require any parameter tuning and is straightforward to use. The algorithm written for polar sampling can be adapted to any sampling scheme and will permit to investigate better compromises in terms of experimental time and lack of artifacts.