Figure 3.

(A) UV-vis spectra of reaction of Cu_BMb (6 μM) with O₂ in the presence of 1,000 equivalents of ascorbate and 100 equivalents of TMPD in 20 mM Tris buffer (pH 8) at 25°C with copper. (B) Time-dependent absorbance changes at 418 and 678 nm with copper (solid line), without copper (dotted line), Ag(I) (short dashed line), and Zn(II) (dotted and dashed line). Absorbance was normalized to the sample containing copper. The spectrum shown in Inset was obtained after addition of 20% pyridine at the maximum formation of verdoheme.