Enhanced Standard Operating Procedures for ³¹P NMR-Based Metabolomics in Tissue Extracts

Phosphorylated metabolites, here referred to as phosphometabolites, are sufficiently abundant and widely distributed to provide a condensed representation of metabolism that can be readily accessed through NMR spectroscopy. This study addresses the challenge of precisely quantifying phosphometabolites via quantitative ³¹P NMR from tissue extracts. We optimized standard operating procedures for enhanced spectral resolution, signal intensity, and accuracy. By amply evaluating solvent and buffer conditions, reference compounds, and paramagnetic relaxation enhancers, we identified optimal conditions for metabolite analysis, including the use of trimethylphosphine oxide for accurate signal referencing due to its short T1 relaxation time and minimal offset and glycine buffer (in D₂O) at pD 9.5, where virtually invariant ³¹P signal frequencies and sample osmolarities are observed, along with maximal NMR detection sensitivity and temperature stability of the pH. These methodological advancements significantly improve the reliability and reproducibility of phosphometabolite characterization, allowing the assignment of up to 60 independent signals in the one-dimensional (1D) ³¹P spectrum (of a total of 94 peaks), that resulted in the proper quantification of 44 phosphometabolites from different tissular samples.