Figure 5.

Formation of the reduced WT ThyX·5F-dUMP·CH₂THF complex. An anaerobic solution of WT ThyX [87 μM active sites (green)] was reduced with 1 equiv of dithionite (blue). An anaerobic solution of 5F-dUMP (300 μM) was added to form the reduced WT ThyX·5F-dUMP complex (red). The anaerobic addition of 400 μM CH₂THF and 15 mM formaldehyde formed the reduced WT ThyX·5F-dUMP·CH₂THF complex (black). The flavin remained reduced indefinitely. These spectra were recorded using a scanning spectrophotometer.