Fig. 6

Zinc ion interferes with ferrous iron binding to TH. A The production of L-dopa in E. coli-expressing TH was elevated by iron and inhibited by zinc added in the media. All values are presented as mean ± SEM and included in Additional file 2: table S8; n = 3. *p < 0.05, **p < 0.01. B Binding of iron to Drosophila TH. Apo-TH was incubated with 15 μM ferrous iron and different concentrations of zinc. Free and bound metal ions were separated by rapid ultrafiltration, and the iron level was determined by BPS-based colorimetric assays. The amount of bound iron decreased with increased zinc concentration in the buffer. All values presented are included in Additional file 2: table S12