Moreover, the mechanism and enzyme site responsible for O-2 generation is unknown.

Furthermore, strong O-2 generation was directly detected from the isolated iNOS reductase domain.

High concentrations of L-arginine decreased this O-2 formation, whereas its enantiomer D-arginine did not.

Conversely, pretreatment of the enzyme with the heme blocker cyanide had no effect on O-2 generation.

Products of the uncoupled reactions are analyzed using diacetyldeuteroheme-substituted horseradish peroxidase as a trapping agent for both O-2.