SITA

Natural-abundance correction for GC-MS mass distribution vectors
from 13C stable-isotope tracer experiments.

[01] correction matrix

Generate the natural-abundance correction matrix for a given fragment. Example: alanine (M–57)+ is C11H26NO2Si2 with 3 backbone carbons.

Number of C atoms subject to 13C labelling (not total C in the fragment). Matrix size is backbone_c + 1.

[02] corrected mdv (mdv*)

Apply the correction matrix to a measured mass distribution vector. Output is normalised to sum to 1.

note: returns MDV* (natural-abundance-corrected) only. Does not apply the unlabelled-biomass correction (Nanchen 2007 Eq. 5). For that, call LabelledCompound.mdv_AA() programmatically.

Comma-separated values summing to ~1. Length must equal backbone_c + 1.

[03] references

The natural-abundance correction math follows:

  1. Nanchen, A., Fuhrer, T., Sauer, U. (2007). Determination of Metabolic Flux Ratios From 13C-Experiments and Gas Chromatography–Mass Spectrometry Data: Protocol and Principles. In: Metabolomics (Methods in Molecular Biology 358), Humana Press, pp. 177–197. doi:10.1007/978-1-59745-244-1_11
  2. Fischer, E., Zamboni, N., Sauer, U. (2004). High-throughput metabolic flux analysis based on gas chromatography–mass spectrometry derived 13C constraints. Analytical Biochemistry 325(2):308–316. doi:10.1016/j.ab.2003.10.036