M.S. THESIS DEFENSE
by
DAVID JOSEPH
Title:
Phase Modulated Selective NMR Methods for Resolving Overlapping Spin Systems and Rapid Data Acquisition: Application in Metabolomics
Wednesday, 10th March 2021 at 11.00 A.M. through MICROSOFT TEAMS
Abstract:
Rapid characterization of complex mixtures of small molecules is crucial in the field of metabolomics. The identification and statistical analysis of small biomolecules can deliver diagnostic biomarkers as well as help in unraveling physiological and pathological pathways, thus can help in therapeutic modulation. In the present study, we developed two new fast NMR methods for the unambiguous assignment of spin systems of complex mixtures of small molecules. Spectra of individual spin systems are obtained using selective excitation of a region and followed by phase modulation (PM) approach that results in different phases for different spin systems from the region. Phase modulation is introduced by evolving the 1H chemical shifts in a conventional one dimensional (1D) selective-TOCSY or two dimensional (2D) selective-TOCSY-HSQC experiments for a fixed delay period. Hence the phase/intensity of a set of peaks belonging to one spin system is modulated differentially relative to those of its overlapping counterpart, resulting in their discrimination and recognition. Thus, the combination of selective excitation of a region and phase modulation accelerates the process of identification and resonance assignment of individual compounds in complex mixtures compared to conventional methods. Rapid assignment of PM selective-TOCSY is obtained using the new in-silico technique. We have used PM selective-TOCSY and PM selective-TOCSY-HSQC approaches successfully for the assignment of metabolites in diverse samples.
Reference
Phase modulated 2D HSQC-TOCSY for unambiguous assignment of overlapping spin systems, Amrinder Singh; Abhinav Dubey; Satish K. Adiga; Hanudatta S. Atreya, Journal of Magnetic Resonance, 2018, 286, 10-16
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