Homo- and Heteronuclear Editing in Proton Spectroscopy

Abstract

Due to its high sensitivity, 100% natural abundance and the ubiquity of the 1H nucleus, 1H NMR provides a sensitive tool for the study of metabolism in vivo. However, the 100 M water resonance, molar lipid resonances, large number of compounds containing 1H nuclei, extensive homonuclear coupling and narrow chemical shift range (10 ppm) of biologically active metabolites provides major barriers to uniquely resolving metabolite resonances of interest and therefore the use of NMR in in vivo biochemical studies. Excellent resolution and identification of 1H resonances of proteins and nucleic acids is commonly achieved by the use of 2-D techniques such as 2 dimensional J-resolved spectroscopy and chemical shift correlated spectroscopy. However, use of these additional dimensions of information encoding (chemical shift evolution of coupled resonances or J-modulation), severely limits the temporal resolution of the experiment, prohibiting its use to observe rapid metabolic changes. To meet this need spectral editing techniques (homonuclear, heteronuclear editing) and polarization transfer sequences have been developed to retain the temporal resolution of a simple one dimensional experiment yet provide the additional spectral resolution of a 2-dimensional experiment for a single resonance (homo-nuclear spectral editing), group of resonances (heteronuclear spectral editing) or class of resonances (polarization transfer).