TY  - GEN
Y1  - 2021///
TI  - Exploring Protein Interactions with 23Na Triple-quantum MRS and 1H Chemical Exchange Saturation Transfer MRI
ID  - heidok29360
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/29360/
CY  - Heidelberg
KW  - Sodium MRI
KW  -  Triple-quantum
A1  - Kleimaier, Dennis
N2  - Nuclear magnetic resonance (NMR) allows the non-invasive investigation of proteins using 23Na triple-quantum (TQ) and 1H chemical exchange saturation transfer (CEST) signals. Interactions of sodium ions with macromolecules yield an intracellular sensitive TQ signal. A TQ signal increase has been shown to correlate with the loss of cell viability. However, a deeper understanding of the TQ signal on a cellular level is necessary to determine its capability to serve as a potential biomarker for cell viability. CEST indirectly detects low concentrated organic compounds by their magnetization transfer with water. Protein-based CEST signals have been demonstrated in vitro to be closely connected to the protein folding state and have great potential as a non-invasive diagnostic tool for diseases, like cancer and neurodegenerative diseases. Nonetheless, the detectability of denaturation processes in living cells by CEST NMR remains to be verified experimentally. In the first part of this thesis, a dependence of the TQ signal on the pH and protein folding state was demonstrated using protein solutions. An increase in the availability of negatively charged groups in proteins caused an increase in the TQ signal during pH variation (224.5 +- 25.1%) or protein unfolding (40.7 +- 2.3%). Second, the cellular response to a Na/K-ATPase inhibition was monitored using improved TQ signal detection. The TQ signal increased by 38.9 +- 4.1% and 83.4 +- 8.9% during perfusion with 1 mM ouabain and 0 mM K+ medium, respectively, which agreed with an influx of sodium ions during the Na/K-ATPase inhibition. Finally, the cellular heat shock response was investigated using protein-based CEST signals. Heat shock application resulted in a substantial signal decrease by 8.0 +- 0.4% followed by a continuous signal recovery, which agreed with chaperone-induced refolding of misfolded proteins. The proposed NMR techniques combined with the bioreactor system are promising research tools to non-invasively investigate cellular processes by NMR.
AV  - public
ER  -