Nuclear magnetic resonance spectroscopy in analyses of biological samples

Abstract

Nuclear magnetic resonance (NMR) spectroscopy can be used for the analysis of almost all biological samples regardless of their complexity and physical state, sometimes requiring minimal sample preparation and handling prior analysis. The variety of molecules for NMR analyses is great from those with very small molecular masses, like metabolites, up to ones with great molecular masses such as proteins and nucleic acids. Nevertheless, for structural analysis of proteins, DNA and RNA or even low molecular mass molecules, there are special requirements for sample preparation with isotope enrichment-common for protein-NMR, samples' purity and many multidimensional experiments. Far more interesting from the bioanalytical applications point of view are NMR applications for complex mixtures studies such as extracts, cells or cell cultures, tissues, and bio-fluids, which require minimal preparations of a sample, dilution, or concentration. Among the most used techniques for lipidomics and metabolomics analyses, we can cite some semisolid and liquid-state NMR mainly based on 1H NMR but also on other spin-active nuclei present in biomolecules, such as 31P, 15N, 13C. This chapter brings some key steps that must be followed when targeting analyses of complex samples by NMR such as sample pretreatment and preparation, correct choice and execution of the most appropriate NMR experiments, then, data and spectral processing, statistical analysis, and identification of key molecules and fingerprints of analyzed samples.