FIGURE 5.

Stopped flow kinetic measurements of iron oxidation after addition of Fe²⁺ to zinc bound BFR and apo-BFR nucleation site mutants. A, inhibition of Phase 2 iron oxidation by various zinc concentrations was measured by stopped flow mixing at 25 °C. 25 μm Fe²⁺ was added to 6 μm BFR dimer in 0.1 m MES buffer (pH 6.5) with [Zn²⁺] = 0, 6, 12, 18, and 24 μm. B, 25 μm Fe²⁺ was added to (i) BFR subunit dimer, (ii) subunit dimer D50N, (iii) subunit dimer D126N, (iv) subunit dimer E47Q, and (v) 6 μm subunit dimer E47Q/D50N/D126N in 0.1 m MES buffer (pH 6.5).