Fig. 2

Redox cofactor specificity of MTHFD2 with CH₂-H₄PteGlu₁. CH₂-THF dehydrogenase activity of purified MTHFD2 was assayed with respect to CH₂-H₄PteGlu₁ concentration using NAD⁺ (1.0 mM) (panel a) or NADP⁺ (6.0 mM) (panel b). NAD⁺-dependent reactions also included 25 mM P _i . The data were fit to the Michaelis-Menten equation. c The ratio of NAD⁺- to NADP⁺-dependent activity plotted as a function of CH₂-H₄PteGlu₁ concentration. The 0–100 μM CH₂-H₄PteGlu₁ range is magnified in panel (d). Data for MTHFD2L from ref. [11]. The shaded boxes in c and d indicate the reported mitochondrial matrix concentration ranges for 5,10-CH₂-THF (2.5–25 μM) [41,42,43]