Figure 8.

Kinetics of ascorbate oxidation monitored at A₂₆₅ in the presence of 5 μM CuCl₂ (gray points) and the series of Cu/His-Leu solutions (6, 12.5, 25, 50, and 100 μM His-Leu) coded point by point from green to violet. The measurements were performed for 100 μM AscH^– in 50 mM HEPES (pH 7.4). The inset represents the initial ascorbate oxidation rate calculated on the basis of the linear fitting of the data between the 13th and 14th minutes of the measurement, overlaid by the molar fraction of bis Cu(II) species (black line) in which the CuL₂ species predominates [>99% bis Cu(II) species].