Figure 6.

Comparison of ²H-incorporation into lipid-derived glycerol and total palmitate in colon cancer cell lines following incubation in 5% ²H₂O for 96 h. Excess molar enrichment in the M₁ isotopomer (EM₁) over time in lipid-derived glycerol (A) and total intracellular palmitate (B) in human colon cancer cell lines grown under identical conditions. Percentage of newly-synthesized palmitate in colon cancer cell lines (C). The experimental maximum (plateau) value represents the percentage of the total intracellular palmitate pool that was de novo derived. The maximum number of exchangeable carbon bound hydrogens (N) in palmitate as determined using MIDA (D). Inset: fractional synthesis rate constant (k), half-life (t_1/2) and goodness-of-fit (R²) from non-linear curve fitting. N values seen in the brackets of the legend (D) are an average of those obtained at the 48-, 72- and 96-h time points; these exhibited the greatest amount of labelling and, therefore, permit the most accurate calculation of N using MIDA. Three replicates were performed for each time point. Error bars represent the standard error of the mean (SEM).