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Published on: September 17, 2017
Quantitative rotational-echo double resonance for Carbon-13 spin clusters
Shigeru Matsuoka1, Miriam Sindelar2, Sonal Bansal2
1Department of Chemistry, Washington University, St. Louis, MO 63130, USA; Faculty of Medicine, Oita University, Oita 879-5593, Japan.
Rotational-echo double resonance (REDOR) for clusters of 13C spins (RDX) achieves quantitative analysis of 13C clusters. This method, RDX24, enables precise characterization of nitrogen isotopic enrichments in cellular proteins.
Area of Science:
- Biophysical Chemistry
- Biochemistry
- Nuclear Magnetic Resonance Spectroscopy
Background:
- Quantitative analysis of 13C spin clusters in biological systems is challenging.
- Traditional REDOR methods struggle with interference from scalar J couplings, limiting their application to isolated spin pairs.
- Developing robust NMR techniques for isotopic enrichment analysis in complex biological samples is crucial.
Purpose of the Study:
- To develop a modified REDOR technique (RDX24) for quantitative analysis of 13C spin clusters.
- To apply RDX24 to characterize nitrogen isotopic enrichments in human embryonic kidney cells.
- To enable precise quantification of metabolic pathways and nutrient utilization through isotopic labeling.
Main Methods:
- Utilized a modified REDOR technique (RDX24) employing half the evolution time for dephasing pulses.
- Combined Hahn echoes with solid echoes to suppress scalar J coupling interference.
- Applied the RDX24 scheme to cultured human embryonic kidney cells labeled with L-[13C5-15N2]-glutamine.
Main Results:
- RDX24 demonstrated universal REDOR behavior for 13C clusters, similar to isolated 13C-15N pairs.
- The RDX24 method proved quantitative for 13C clusters.
- Successfully characterized three distinct nitrogen isotopic enrichments in cellular components.
Conclusions:
- RDX24 offers a robust and quantitative method for analyzing 13C spin clusters in biological systems.
- The technique allows for detailed characterization of nitrogen isotopic enrichments in proteins and amino acids.
- This advancement provides a powerful tool for metabolic flux analysis and understanding cellular biosynthesis.
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