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. Author manuscript; available in PMC: 2022 Oct 9.
Published in final edited form as: Anal Chim Acta. 2021 Jul 26;1181:338873. doi: 10.1016/j.aca.2021.338873

Figure 5. 13C Isotopologue distributions of SAM, SAH and their precursors in A549 cells grown on 13C6-glucose or 13CH3-methionine.

Figure 5.

A549 cells were grown under standard conditions in media containing no 13C-enriched tracers, 13C6-glucose (13C6-Glc) or 13CH3-methionine (13CH3-Met) as described in Experimental. The tracer experiments were done with n=3 and unlabeled experiment with n=2. Values on the X-axis denote the number of 13C for each isotopologue. SAM and SAH were measured using the described method, and other metabolites were measured using the method described in ref 36.
  1. Fractional distribution of metabolite isotopologues in the pentose phosphate pathway (PPP) and those of the downstream products phosphoribosyl pyrophosphate (PRPP), ATP, SAM, and SAH in 13C6-glucose grown samples. The atom tracing scheme depicts the more abundant isotopologue species resulting from the transformation of 13C6-Glc via the PPP. G6P: glucose-6-phosphate; 6PG: 6-phosphogluconate; R5P: ribose/ribulose-5-phosphate; X5P: xylulose-5-phosphate; S7P: sedoheptulose-7-phosphate; E4P: erythrose-4-phosphate; F6P: fructose-6-phosphate; G6PDH: glucose-6-phosphate dehydrogenase; 6PGDH: 6-phosphogluconate dehydrogenase; TK: transketolase; TA: transaldolase.
  2. Ratio of the 13C6- to 13C7-isotopologues of ATP and SAM derived from 13C6-Glc. A higher ratio in SAM than that in ATP reflect 13C labeling in the methyl group of SAM. ***: p-value 0.0012
  3. Fractional distribution of isotopologues of SAM and SAH in 13CH3-Met grown samples.