Comparison of experimental and predicted mass isotopomer distributions during growth of wild-type G. sulfurreducens on acetate-fumarate medium containing unlabeled acetate and 30% [13C]fumarate

Amino acid and mass isotopomeraExperimental mass isotopomer distributionbPredicted MDVc
Threonine pathwayCitramalate pathwayBoth pathways
Total errord 0.37840.12710.0622
  • a The unlabeled molecule is shown as M+0, and numbers above zero correspond to the number of additional mass units (13C atoms).

  • b Experimental values are averages of two fragments for each amino acid, both missing the carboxy-terminal carbon atom. The mass isotopomer distributions for these two fragments were the averages of three derivatizations performed on extracts prepared from pooled duplicate cultures.

  • c MDVs were calculated by running the optimization routine assuming each pathway separately, and then allowing the optimization routine to select the best-fitting ratio between them.

  • d Errors are the sum of squared differences between predicted and experimental values for aspartate, isoleucine, and leucine fragments.