Direct measurement of nitric oxide (NO) production rates from enzymes using ozone-based gas-phase chemiluminescence (CL).

Nitric oxide (NO) chemiluminescence detectors (CLDs) are specialized and sensitive spectroscopic instruments capable of directly measuring NO flux rates. NO CLDs have been instrumental in the characterization of mammalian nitrite-dependent NO synthases. However, no detailed description of NO flux analysis using NO CLD is available. Herein, a detailed review of the NO CL methodology is provided with guidelines for measuring NO-production rates from aqueous samples, such as isolated enzymes or protein homogenates. Detailed description of the types of signals one can encounter, data processing, and potential pitfalls related to NO flux measurements will also be covered.