By using high-resolution mass spectrometry, potential inhibitors were identified to be precursors or analogs of ABTS.
The inhibition of horseradish peroxidase (HRP) is uncompetitive for the substrate H 2O 2 while it is competitive for the substrate ABTS. We show that the impurities inhibit the activity of the peroxidases and the influence varies for different batches of ABTS from the same source. We discovered that impurities in the commercially available ABTS significantly affect the results of peroxidase activity assays. ABTS, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate), is a common chromogenic substrate for peroxidase enzymes, which are widely used in biochemical research and diagnostic tests.
