Skip to main content
. Author manuscript; available in PMC: 2011 Feb 15.
Published in final edited form as: Free Radic Biol Med. 2009 Nov 24;48(4):493–498. doi: 10.1016/j.freeradbiomed.2009.11.012

Fig. 1. H2O2 is the major ROS produced by XO at low O2 tensions.

Fig. 1

(A) XO (20 mU/ml, PBS pH 7.2) was exposed to xanthine (100 µM) in a 1% O2 atmosphere and O2 concentration monitored polargraphically over time. (B) During the linear phase of O2 consumption 50 U/ml catalase (CAT) (2H2O2 → 2H2O + O2) was added to the reaction. (C) Scheme showing total O2 evolved (2.1 µM) by the addition of 50 U/ml CAT at 1% O2 and the effect of increasing O2 tension (1–5%) on the quantity of CAT-dependent O2 evolution. (D) Using the quantity of O2 evolved at 1% O2 as maximum (100%), CAT-dependent O2 evolution values are plotted as (% Maximum) for O2 concentrations (1–21%). For each O2 tension, CAT was added to the samples immediately after the same XO-dependent depletion of O2 (4.7 µM). Values represent the mean of at least 4 independent determinations.