Figure 3

Reconstitution of apoforms of TKT ^C (A) and TKT ^P (B) in the presence of different divalent cations. The reaction was measured according to the enzyme assay I (Methods) with the standard substrates R5-P and X5-P and dialyzed TKT preparations. Each reaction mixture contained 1 mM divalent cations and 150 ng purified TKT enzyme. At t = 0, the assay was started by the addition of THDP to a final concentration of 20 μM. The decrease in absorbance at 340 nm as a result of NADH oxidation was monitored over time.