FIGURE 8.

AdoMet has no effect on the reduction or oxidation kinetics of the CBS heme. A, time courses of ferric CBS (1.4–1.5 μm in heme content, before mixing) reduction by sodium dithionite (1 mm before mixing) in the absence (dotted line) or presence (solid line) of AdoMet (500 μm before mixing). T = 25 °C. Fitted rate constants (% reaction amplitude) are as follows: k₁ =0.33 s⁻¹ (10%) and k₂ = 0.09 s⁻¹ (90%). B, time courses of CBS oxidation by oxygen (240 μm before mixing) in the absence (dotted line) and presence (solid line) of AdoMet (500 μm before mixing). T = 25 °C. Buffer consisted of 50 mm potassium phosphate, 300 mm KCl, 10% glycerol, pH 7.0, containing 2 mm glucose, 4 units/ml glucose oxidase, 13 μg/ml catalase, and 60 units/ml SOD. Traces were best fitted with k = 19.9 ± 1.4 s⁻¹ and k = 23.2 ± 2.2 s⁻¹ in the absence (dotted line) and presence (solid line) of AdoMet, respectively.