The use of indole as a spectrophotometric assay substrate for toluene dioxygenase

Abstract Cell extracts of toluene-grown Pseudomonas putida produced a soluble yellow dye during aerobic incubations with indole and NADH. Accumulation of indoxyl in reaction mixtures corresponded with a linear increase in absorbance at 400 nm. The rate of increase in absorbance was shown to be a specific measure of toluene dioxygenase activity. The primary product of toluene oxidation, cis -toluene dihydrodiol, inhibited dioxygenase activity in cell extracts containing no detectable activity of cis -toluene dihydrodiol dehydrogenase.