Inhibition of Fe mineralization in Cr(TREN)–ferritin complexes.
Mineralization as a function of [Cr(TREN)] bound per protein subunit
is shown. Ferritins (2 μM) were preincubated with Cr(TREN) (0–2.5
mM) for 24 h at 25°C, Fe(II) was added {500 Fe(II) per
protein, [Fe] = 1 mM}, and after 2 h incubation, unmineralized
Fe was separated from the protein by electrophoresis in native
polyacrylamide gels (6%). Mineralization was monitored as the density
of Prussian blue formed in protein bands after soaking acidic solutions
of potassium ferrocyanide. For each protein, the amount of iron
mineralization is shown relative to the iron cores formed in the
absence of Cr(TREN). The average of multiple experiments is shown;
there was little variation observed in replicate experiments. The
number of independent measurements for each type of protein is
indicated, with the number of independent protein preparations shown in
parenthesis: rH = 3 (1), rH L134P = 4 (3), HoSF = 4 (2),
rL = 2 (2), E2 = 2 (1).