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Spin-spin interaction in ethanolamine deaminase
1Department of Physics, National Dong Hwa University, Hualien 974-01, Taiwan. ke@mail.ndhu.edu.tw
Biochimica Et Biophysica Acta
|February 22, 2003
Summary
Salmonella typhimurium ethanolamine deaminase uses a radical intermediate during aminoethanol breakdown. Simulations of electron paramagnetic resonance (EPR) spectra confirm it
Area of Science:
- Biochemistry
- Enzymology
- Spectroscopy
Background:
- Ethanolamine deaminase from Salmonella typhimurium is a coenzyme B12-dependent enzyme.
- It catalyzes the deamination of aminoethanol to acetaldehyde and ammonia.
- A radical intermediate is observed during substrate turnover.
Purpose of the Study:
- To simulate and characterize the EPR spectra of the radical intermediate.
- To compare the interaction of the aminoethanol-derived radical with the enzyme-bound cobalt(II) to that of a substrate analog radical.
- To confirm the nature of the radical intermediate.
Main Methods:
- Continuous wave electron paramagnetic resonance (EPR) spectroscopy.
- Spectra simulations using models of isotropic exchange and magnetic dipolar interaction.
- Analysis of isotope substitutions (e.g., 13C, 1H).
Main Results:
- Quantitative fits to EPR spectra were achieved.
- The aminoethanol-derived radical interacts more weakly with Co(II) than the 2-aminopropanol-derived radical.
- The radical intermediate was confirmed as a pi-electron-based product radical.
- Experimental hyperfine coupling constants were determined for 13C(alpha) and 1H(alpha).
Conclusions:
- The study provides reliable experimental hyperfine coupling constants for the radical intermediate.
- These constants can be used for comparison with quantum mechanical calculations.
- This offers further insight into the molecular structure of the radical intermediate.