glyphosate,
AMPA, and N-methylAMPA (MeAMPA), having ΓΌltered out interfering signals from unlabeled molecules. MOPS peaks are comparable in size to those of the low concentration metabolites, as seen by comparison of the 2H spectrum of a sample of the mixed Dworkin-Foster/MOPS medium alone (B) with that of the 33-h incubation (C). This background signal led to difficulties in deΓΌnitively assigning metabolites in the deuterium spectrum, as did uncancelled MOPS peaks in the TRIED spectrum. [2H-13C] INEPT was utilized in an attempt to minimize interactions by combining magnetization transfer from deuterium to carbon. An 80 mM MOPS solution in of approx-D 2 O imately 15 mg of dideuterated glyphosate (13C-15N-13C-labeled, 75% 2H-enriched at the carboxymethylene protons) was prepared and studied by (A) proton, (B) proton, and (C) [2H-13C] INEPT, Fig 2. MOPS is again the dominant feature of both the proton and carbon spectra. In the [2H-13C] INEPT spectrum, however, only resonances resulting from the carboxymethylene of the glyphosate are detected. The MOPS peaks have been ΓΌltered out, leaving only the resonances of the desired compound. [2H-13C] INEPT has a theoretical molar cancellation efficiency of greater than 5 ] 105 :1 in addition to the increased chemical shift dispersion of carbon. Together, TRIED, [2H]NMR and [2H-13C] INEPT form a powerful arsenal of isotopeedited techniques for the study of glyphosate metabolism in extracts from biological systems.
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