Fig 4.

(A) Curve a shows an absorption spectrum of 100 μM VA after 24 h in the presence of 1.0 mM FeCl₃ in physiological oxalate. For comparison, curve b shows the absorption spectrum of VAQM produced by the reaction of 100 μM VA with laccase as described in Materials and Methods. (B) Absorption spectra obtained from the reaction of 50 μM DMHQ with 50 μM FeCl₃ in physiological oxalate. Spectra are shown for the following reaction times (in minutes): 0.2 (curve a), 7.0 (curve b), 20.0 (curve c), 49.0 (curve d), 110.0 (curve e), and 225.0 (curve f).