TABLE 3.

Time-dependent ¹⁴CO₂ generation by epimastigote form from l-[3¹⁴C]Ser, l-[U¹⁴C]Thr, and [U¹⁴C]Gly^a

	Time (min)	14CO2 (nmol/1 × 107 cell)	Uptake (nmol/1 × 107 cell)	% recovered 14CO2d
l-Ser	30	0.24 ± 0.02b	9.18 ± 1.06	2.61
	60	2.67 ± 0.23b	14.11 ± 0.84	18.93
	180	16.59 ± 0.62b	25.47 ± 1.1	65.1
l-Thr	30	0.27 ± 0.1	5.28 ± 0.35	5.08
	60	0.81 ± 0.22	10.19 ± 1.04	7.99
	180	3.74 ± 0.22	17.72 ± 1.05	21.08
Gly	30	0.09 ± 0.07c	17.31 ± 1.73	0.52
	60	0.01 ± 0.02c	21.33 ± 1.02	0.07
	180	0.19 ± 0.38c	29.38 ± 1.02	0.65

^a All data were shown as mean ± SD (n = 3). All experiments were replicated three times or more in three biological replicates.

^b Considering that the only way for l-[3¹⁴C]Ser to be released as CO₂ is through complete degradation in the TCA cycle, the obtained value was normalized by multiplying it by 3. In contrast, the values obtained for l-[U-¹⁴C]Thr or [U-¹⁴C]Gly have not been normalized since all carbon are ¹⁴C-labeled.

^c Considering the standard error, the percentage of ¹⁴CO₂ produced from Gly was assumed to be residual and may have originated from the residual activity of the glycine cleavage complex.

^d To assess the comparative release of carbon as CO₂, the measured values were normalized against the quantity of the transported amino acid over the identical incubation duration detected in Fig. 1A through C.