I am setting up mitochondrial complex specific assays performed with a spectrophotometer. I am interested in setting up the assay to look at complex IV activity using the electron donor TMPD. Upon metabolism of TMPD by mitochondrial complex IV the amount of oxidized product of this chemical should increase and therefore the absorbance of the absorbance maxima of the oxidized TMPD. At what wavelength does the absorbance of reduced and oxidized TMPD differ maximally so that I can correlate amount of oxidized TMPD with complex IV activity?