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Hyperpolarized 13C Metabolic Magnetic Resonance Spectroscopy and Imaging
Published on: December 30, 2016
Probing alanine transaminase catalysis with hyperpolarized 13CD3-pyruvate
A W Barb1, S K Hekmatyar, J N Glushka
1Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602, United States.
Journal of Magnetic Resonance (San Diego, Calif. : 1997)
|January 30, 2013
Summary
Hyperpolarized (13)C3D(3)-pyruvic acid reveals alanine transaminase (ALT) mechanisms. This method detected an enamine intermediate, offering new insights into liver disease biomarkers.
Area of Science:
- Biochemistry
- Medical Imaging
- Metabolic Engineering
Background:
- Hyperpolarized metabolites provide >10,000-fold sensitivity enhancement for magnetic resonance studies.
- This sensitivity is crucial for mechanistic investigations under time and concentration constraints.
- Alanine transaminase (ALT) is a key biomarker for liver disease and cancer.
Purpose of the Study:
- To investigate the reaction mechanism of alanine transaminase (ALT) using hyperpolarized (13)C3D(3)-pyruvic acid.
- To explore the utility of hyperpolarized tracers in mechanistic enzyme studies.
- To assess the potential for imaging applications using mechanism-dependent molecular signatures.
Main Methods:
- Utilized dissolution dynamic nuclear polarization (DNP) to hyperpolarize (13)C3D(3)-pyruvic acid.
- Employed direct (13)C observation and indirect proton observation via H-D exchange for detection.
- Measured proton incorporation into alanine products on a 1.5-second timescale.
Main Results:
- Observed ALT-catalyzed H-D exchange, introducing protons into the alanine methyl group.
- Quantified an average of 0.8 new protons per alanine molecule produced.
- Identified evidence for an off-pathway enamine intermediate in the ALT reaction.
Conclusions:
- Hyperpolarized (13)C3D(3)-pyruvate enables rapid, mechanistic studies of ALT.
- The detection of an enamine intermediate provides novel mechanistic insights.
- This approach holds promise for developing mechanism-based imaging biomarkers.
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