Figure 3.

Time course of the ring expansion of penicillin G by resting cells. The reaction contained 50 mM Tris⋅HCl (pH 7.4), 4 mM ascorbic acid, and 2 mg/ml penicillin G. Cell mass was 11.6 mg/ml in both cases. ■, old concentrations (0.04 mM FeSO₄, 0.64 mM α-ketoglutarate); •, new concentrations (1.8 mM FeSO₄, 1.28 mM α-ketoglutarate). Samples were taken and were centrifuged (14,000 × g, 5 min); 200 μl was used in the bioassay.