Reversible Binding and Inhibition of Catalase by Nitric Oxide

The interactions between nitric oxide (NO), H2O2, and catalase were investigated. H2O2 did not cause detectable breakdown of NO in the absence of catalase, but did cause NO breakdown in the presence of catalase. Catalase bound NO, and NO rapidly and reversibly inhibited catalase with a Ki of 0.18 microM. The significance of these results for NO cytotoxicity is discussed.