2D and 3D maximum-quantum NMR and diffusion spectroscopy for the characterization of enzymatic reaction mixtures.

1D H NMR spectroscopy has been widely used to monitor enzymatic activity by recording the evolution of the spectra of substrates and/or products, thanks to the linear response of NMR. For complex systems involving the coexistence of multiple compounds (substrate, final product and various intermediates), the identification and quantification can be a more arduous task. Here, we present a simple analytical method for the rapid characterization of reaction mixtures involving enzymatic complexes using Maximum Quantum (MaxQ) NMR, accelerated with the Non-Uniform Sampling (NUS) acquisition procedure.

Evaluation of the Rotating-Frame Relaxation () Filter and Its Application in Metabolomics as an Alternative to the Transverse Relaxation () Filter.

Nuclear magnetic resonance (NMR)-based metabolomic studies commonly involve the use of filter pulse sequences to eliminate or attenuate the broad signals from large molecules and improve spectral resolution. In this paper, we demonstrate that the filter-based pulse sequence represents an interesting alternative because it allows the stability and the reproducibility needed for statistical analysis. The integrity of the samples and the stability of the instruments were assessed for different filter durations and amplitudes.

Challenges in the decomposition of 2D NMR spectra of mixtures of small molecules.

Analytical methods for mixtures of small molecules require specificity (is a certain molecule present in the mix?) and speciation capabilities. NMR spectroscopy has been a tool of choice for both of these issues since its early days, due to its quantitative (linear) response, sufficiently high resolving power and capabilities of inferring molecular structures from spectral features (even in the absence of a reference database). However, the analytical performances of NMR spectroscopy are being stretched by the increased complexity of the samples, the dynamic range of the components, and the need for a reasonable turnover time.