Figure 6.

Oxidative half-reactions of variant enzymes. The reduced variant enzyme·dUMP complexes were mixed with saturating concentrations CH₂THF using a stopped-flow spectrophotometer. The reactions were monitored by their absorbance at 420 nm. The reaction mixtures were in 0.1 M Tris-HCl (pH 8.0) with 1 mM EDTA and 15 mM CH₂O at 25 °C. Traces, labeled by ThyX variant, are displayed in two panels for the sake of clarity.