Table I.
Predicted and observed 13C enrichments of Ala, reflecting dual pathways of synthesis in oxygenated [1-13C]Glc-labeled maize root tips
| C | Pathway
|
||
|---|---|---|---|
| Glycolysis only (Glc-6-P → Ala)a | ME (Malate → Ala)a | Glycolysis + MEb | |
| % | |||
| C1 | 1.1 | 7.42 ± 1.6 | 2.16 ± 0.36 |
| C2c | 1.1 | 17.45 ± 1.2 | 1.59 ± 0.37 |
| C3 | 31.92 ± 3.88 | 17.54 ± 2.0 | 25.73 ± 2.1 |
Predicted enrichments of Ala synthesized exclusively via either glycolysis or ME activity were deduced from 13C enrichments of Glc-6-P and malate, respectively. Values are means ± sd (n = 4).
a
Predicted.
b
Observed in vivo.
c
Only C2 Ala was used to measure in vivo ME activity (see text).