Fig. 6.

Kinetic characteristics of reduction of Mb³⁺ and Cygb³⁺ by different concentrations of Asc. A: Reduction of Mb³⁺ by 10 mM and 30 mM Asc. B: Simultaneous measurements of Cygb³⁺ reduction and Cygb²⁺ formation at different Asc concentrations. The reaction process of Cygb³⁺ with Asc was recorded by repetitively scanning from 350 nm and 700 nm on a Cary 50 UV/VIS spectrophotometer while different concentrations of Asc (0.1, 0.2, 0.7, 2, 7, 20 mM) were injected into the chamber at the time indicated by vertical lines. The kinetic curves of Cygb³⁺ reduction and Cygb²⁺ formation can be observed by plotting the absorbance changes vs. time at wavelength 416 nm or 428 nm.