Extended Data Fig. 7: Isotope-tracing experiments aid the identification of N-propionyl-AAs.
From: C. elegans as a model for inter-individual variation in metabolism
a, EICs for m/z 172.0979 and 177.1147, corresponding to C8H14NO3- and 13C5-C8H14NO3-, from exo-metabolome extracts of N2 supplemented with Val or 13C5-Val. Red dashed line highlights metabolite with 13C5-enrichment, corresponding to N-propionyl-Val. EIC Y-axis for m/z 177.1147 is scaled 20-fold to more clearly show traces for labelled features. Isotopic labelling is highlighted by green shading in the structure of N-propionyl-Val. b, EICs for m/z 186.1136 and 192.1337, corresponding to C9H16NO3- and 13C6-C9H16NO3-, from exo-metabolome extracts of N2, supplemented with Leu or 13C6-Leu. Red dashed line highlights metabolite with 13C6-enrichment, corresponding to N-propionyl-Leu. Isotopic labelling is highlighted by green shading in the structure of N-propionyl-Leu. c, Major MS/MS fragmentation (negative ion mode) of N-propionyl-AAs and resulting fragment ions representing different amino acids. d, Quantification of N-propionyl-AAs from endo- and exo-metabolome extracts of the four strains. Data represent five or six biologically independent experiments for the endo- or exo-metabolomes, respectively, and bars indicate mean ± s.d. Y-axis scaling is maintained across graphs. e, Quantification of N-propionyl-AAs in exo-metabolome extracts of N2 and hphd-1(ok3580) animals. Data represent four biologically independent experiments and bars indicate mean ± s.d. f, Quantification of N-propionyl-AAs in exo-metabolome extracts of the DL238 strain fed the standard E. coli OP50 diet without or with supplementation of 64 nM vitamin B12, as indicated. Data represent three biologically independent experiments and bars means ± s.d. For d, e, and f, p-values calculated by two-sided, unpaired t-test with Welch correction. ns, not significant. Source data are provided as a Source Data file.
