Reexamination of the 1H NMR assignments and solution conformations of l-carnitine and O-acetyl-l-carnitine using C-2 stereospecifically labeled monodeuterated isomers

Fred Brewer, Hermann Seim, Sasha Englard

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Abstract

The two C-2 monodeuterated isomers of l-carnitine were synthesized by enzymatic hydration of crotonobetaine in D2O and by enzymatic proton exchange of l-[2-2H2] carnitine in H2O. These reactions, catalyzed by an induced Escherichia coli carnitine hydrolyase proceed stereospecifically. The two isomers of l-[2-2H]carnitine were examined by 1H NMR at 500 MHz, which allowed us to independently monitor the pD dependence and coupling constants of the H-2 protons. The results obtained indicate that there is little effect of the carboxyl charge on the conformational state(s) of l-carnitine about the C-2/C-3 bond. The NMR data obtained in this study do not support previous solution studies of the pH-dependent conformational changes for dl-carnitine nor the proposed conformation of O-acetyl-dl-carnitine in the crystalline state.

Original languageEnglish (US)
Pages (from-to)495-499
Number of pages5
JournalArchives of Biochemistry and Biophysics
Volume276
Issue number2
DOIs
Publication statusPublished - Feb 1 1990

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ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology

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