Figure 4.

Reaction of the reduced WT ThyX·5-dUMPS complex with CH₂THF. Anaerobic solutions of reduced WT ThyX (14 μM active sites) and dUMP [300 μM (black)] or with 5-dUMPS [300 μM (blue)] were mixed with 400 μM CH₂THF and 15 mM formaldehyde using a stopped-flow spectrophotometer. The reaction mixtures were in 0.1 M Tris-HCl (pH 8.0) with 1 mM EDTA and 15 mM CH₂O at 25 °C.