Singular spectrum analysis for an automated solvent artifact removal and baseline correction of 1D NMR spectra.
J Magn Reson. 2011 Mar 6;
Authors: De Sanctis S, Malloni WM, Kremer W, Tomé AM, Lang EW, Neidig KP, Kalbitzer HR
NMR spectroscopy in biology and medicine is generally performed in aqueous solutions, thus in (1)H NMR spectroscopy, the dominant signal often stems from the partly suppressed solvent and can be many orders of magnitude larger than the resonances of interest. Strong solvent signals lead to a disappearance of weak resonances of interest close to the solvent artifact and to base plane variations all over the spectrum. The AUREMOL-SSA/ALS approach for automated solvent artifact removal and baseline correction has been originally developed for multi-dimensional NMR spectroscopy. Here, we describe the necessary adaptations for an automated application to one-dimensional NMR spectra. Its core algorithm is still based on singular spectrum analysis (SSA) applied on time domain signals (FIDs) and it is still combined with an automated baseline correction (ALS) in the frequency domain. However, both steps (SSA and ALS) have been modified in order to achieve optimal results when dealing with one-dimensional spectra. The performance of the method has been tested on one-dimensional synthetic and experimental spectra including the back-calculated spectrum of HPr protein and an experimental spectrum of a human urine sample. The latter has been recorded with the typically used NOESY-type 1D pulse sequence including water pre-saturation. Furthermore, the fully automated AUREMOL-SSA/ALS procedure includes the managing of oversampled, digitally filtered and zero-filled data and the correction of the frequency domain phase shift caused by the group delay time shift from the digital finite response filtering.
PMID: 21459640 [PubMed - as supplied by publisher]
Origin and removal of mixed-phase artifacts in gradient sensitivity enhanced heteronuclear single quantum correlation spectra
Origin and removal of mixed-phase artifacts in gradient sensitivity enhanced heteronuclear single quantum correlation spectra
Abstract Here we describe phasing anomalies observed in gradient sensitivity enhanced 15N-1H HSQC spectra, and analyze their origin. It is shown that, as a result of 15N off-resonance effects, dispersive contributions to the 1H signal become detectable, and lead to 15N-offset dependent phase errors. Strategies that effectively suppress these artifacts are presented.
Content Type Journal Article
Category Article
Pages 199-207
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Sequence correction of random coil chemical shifts: correlation between neighbor correction factors and changes in the Ramachandran distribution
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Authors: Weigelt J, Hammarstroem A, Bermel W, Otting G
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[NMR paper] Probing protein structure by solvent perturbation of NMR spectra. Photochemically ind
Probing protein structure by solvent perturbation of NMR spectra. Photochemically induced dynamic nuclear polarization and paramagnetic perturbation techniques applied to the study of the molten globule state of alpha-lactalbumin.
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Automated solvent artifact removal and base plane correction of multidimensional NMR
Abstract Strong solvent signals lead to a disappearance of weak protein signals close to the solvent resonance frequency and to base plane variations all over the spectrum. AUREMOL-SSA provides an automated approach for solvent artifact removal from multidimensional NMR protein spectra. Its core algorithm is based on singular spectrum analysis (SSA) in the time domain and is combined with an automated base plane correction in the frequency domain. The performance of the method has been tested on synthetic and experimental spectra including two-dimensional NOESY and TOCSY spectra and a...