Development of isotags for NMR based metabolite profiling and applications
NMR spectroscopy is a powerful analytical tool for both qualitative and quantitative metabolite profiling analysis. However, accurate quantitative analysis of biological systems especially using one dimensional NMR has been challenging due to signal overlap. In contrast, the enhanced resolution and sensitivity offered by chemoselective isotope tags have enabled new and enhanced methods for detecting hundreds of quantifiable metabolites in biofluids using NMR spectroscopy or mass spectrometry. In this thesis we show improved sensitivity and resolution of NMR experiments imparted by 15N and 13C isotope tagging which enables the accurate analysis of plasma metabolites. To date, isotope tagging has been used in conjunction with a single analytical platform. The inability to detect the same metabolites using the complementary analytical techniques of NMR and mass spectrometry has hindered the correlation of data derived from the two powerful platforms for applications such as biomarker discovery or the identification of unknown metabolites. To address this problem, we describe a smart isotope tag, 15N-cholamine, which possesses two important properties: an NMR sensitive isotope, and a permanent charge for MS sensitivity. Finally, we present a study on metabolite profiling using intact breast cancer tissue samples in which we exploit the combined strength of NMR and multivariate statistical methods for metabolite profiling.
Thompson, Purdue University.
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