Nitric oxide oxidises a ferrous mammalian lipoxygenase to a pre-activated ferric species.

Nitric oxide is known as an inhibitor of soybean lipoxygenase-1. Investigating the interaction of a mammalian 15-lipoxygenase with nitric oxide, we found that this enzyme is also inhibited reversibly when incubated with nitric oxide for a short time period (5 s) under anaerobic conditions. This inhibition may be due to the formation of a dissociable lipoxygenase-nitric oxide complex. With longer incubation periods the ferrous lipoxygenase is oxidised to a ferric form. This oxidation renders the enzyme more susceptible to peroxide activation, causing a time-dependent shortening of the kinetic lag phase.