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Methods to Identify the NMR Resonances of the 13C-Dimethyl N-terminal Amine on Reductively Methylated Proteins
Published on: December 12, 2013
Migration of methyl groups between aliphatic amines in water
Brian P Callahan1, Richard Wolfenden
1Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, 27599-7260, USA.
Journal of the American Chemical Society
|January 9, 2003
Summary
Glycine decarboxylation produces methylamines that further react. Methylamines undergo disproportionation in water, yielding other methylamines, a novel finding in chemical kinetics.
Area of Science:
- Organic Chemistry
- Chemical Kinetics
- Reaction Mechanisms
Background:
- Glycine decarboxylation in aqueous solution at elevated temperatures yields methylamine.
- Unexpectedly, dimethylamine and trimethylamine also appeared, suggesting further reactions.
Purpose of the Study:
- To investigate the spontaneous formation of methylamines from glycine.
- To explore the proposed methylamine disproportionation reactions in aqueous media.
- To elucidate the kinetics and mechanism of methylamine transformations.
Main Methods:
- Monitoring amine product formation over time.
- Investigating reaction rates as a function of pH using amine buffers.
- Studying methyl group migration in N,N-dimethyl-1,3-propanediamine.
- Comparing the reactivity of sulfonium ions as methyl group donors.
Main Results:
- Methylamine, dimethylamine, and trimethylamine were observed to interconvert.
- The rate of methylamine disproportionation peaked at equivalent concentrations of protonated and unprotonated amine species.
- Methyl group migration in diamines followed first-order kinetics.
- Trimethylsulfonium ion demonstrated significantly higher reactivity than tetramethylammonium ion in methyl group transfer.
Conclusions:
- Glycine decarboxylation initiates a cascade of methylamine disproportionation reactions in water.
- The pH-dependent kinetics support a mechanism involving both protonated and unprotonated amine species.
- Methyl group transfer reactions are influenced by the structure of the methylating agent and the acceptor.
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