Skip to main content
. 2017 Aug 21;114(36):E7574–E7582. doi: 10.1073/pnas.1619034114

Fig. 4.

Fig. 4.

2-KG conversion to d-2-HG couples and drives d-3-PG dehydrogenation. (A) Thermodynamic analysis of the reactions in the l-serine biosynthesis pathway indicates that d-2-HG production serves SerA to facilitate d-3-PG dehydrogenation and l-serine biosynthesis. The ΔG°′obs values were calculated using the following formula: ΔG°′obs = −RTlnKobs. The Kobs value is the observed equilibrium constant of the reaction performed at 38 °C, pH 7.0 in previous studies. 3-PS, 3-phosphoserine. (B) The activities of 2-KG reduction reaction (2-KG, 5 mM; NADH, 0.2 mM) and d-3-PG dehydrogenation reaction (d-3-PG, 10 mM; NAD+, 1 mM) catalyzed by SerA (0.28 μM). (C) HPLC analysis of the products of the reaction coupled by SerA and SerC (heat-inactivated enzymes as a control). The mixtures containing NAD+ (4 mM), l-glutamate (10 mM), d-3-PG (20 mM), SerC (1.2 mg·mL−1), and SerA (1.03 mg·mL−1) in 50 mM Tris (pH 7.4) were reacted at 30 °C for 3 h.