Normalized Labeling
Found in the PeakGroups data format.
Normalized Labeling is the enrichment of a label in a compound normalized to the enrichment of that label among the tracer compound(s) from the final serum timepoint for an animal. This is calculated for each labeled element separately.
normalized_labeling = enrichment_fraction / serum_tracers_enrichment_fraction
See:
Example
normalized labeling in alanine (C3H7NO2) and glutamate (C5H9NO4) measured in the final serum sample and one tissue (quadricep) sample from an infusion of [13C3-15N]-alanine:
| Tissue | Measured Compound(s) |
Labeled Element |
Total Abundance |
Enrichment Fraction |
Enrichment Abundance |
Normalized Labeling |
|---|---|---|---|---|---|---|
| serum_plasma_tail | alanine | C | 1721209 | 0.275916 | 474909.5 | 1 |
| serum_plasma_tail | alanine | N | 1721209 | 0.344919 | 593677.6 | 1 |
| serum_plasma_tail | glutamate | C | 242215.7 | 0.018 | 4359.787 | 0.065236 |
| serum_plasma_tail | glutamate | N | 242215.7 | 0.053935 | 13063.83 | 0.156369 |
| quadricep | alanine | C | 97694902 | 0.006183 | 604078.4 | 0.02241 |
| quadricep | alanine | N | 97694902 | 0.019993 | 1953218 | 0.057964 |
| quadricep | glutamate | C | 14251992 | 0.007268 | 103580.9 | 0.026341 |
| quadricep | glutamate | N | 14251992 | 0.087257 | 1243586 | 0.252978 |
In some cases, a labeled element present in a tracer is not found in a measured compound, and Normalized Labeling is not reported. For example, lactate (C3H6O3) can be measured in samples from an animal infused with N-labeled glutamine (C5H10N2O3), but no nitrogen enrichment or normalized labeling is reported for lactate.
For infusates with multiple tracers, the serum tracers enrichment fraction is the average of enrichment in each serum tracer group.
The selection of the serum tracer peak groups to use, when multiple instances have been picked, depends on the following:
- If multiple serum samples were collected on the same date and same minutes after the start of infusion, (i.e. they are biological replicates), the specific tracer peak group selected for each tracer is arbitrary.
- If a serum tracer peak group is present in multiple MSruns (appears in multiple AccuCor files), the most recently uploaded data is selected.