Luciferase from Photinus pyralis (firefly)

Firefly luciferase is used extensively in molecular and cell biology, in particular for the efficient detection and quantitation of ATP and as a reporter for genetic function.

Firefly luciferase is a 62 kDa protein that catalyzes the production of light. The enzyme requires ATP, molecular oxygen, and the heterocyclic compound, firefly luciferin, to generate light in a two-step process. The light producing reaction is initiated by luciferin activation (adenylation of its carboxylate group) and proceeds in the presence of molecular oxygen to yield a photon of yellow-green light.

Supplied as a lyophilized powder containing HEPES, pH 7.5, NaCl, MgCl₂, EDTA, DTT and a carbohydrate stabilizer.

This product is a recombinant luciferase (62 kDa) from Photinus pyralis (American firefly) produced from the luc gene expressed in E. coli.

To obtain maximal solubility it is important to reconstitute the enzyme at a high salt concentration, such as 1 M Tris buffer with any counter ion at pH 7-8. The enzyme can be prepared at a concentration of up to 5 mg protein/ml. Do not vortex and avoid agitation.
After reconstitution, the enzyme solutions can kept at 4-8 °C for up to 2 days or frozen in working aliquots at -20°C for at least one month. Repeated freezing and thawing is not recommended.

One luciferase enzyme unit will produce one Relative Light Unit (RLU) at 20-25 °C over a 10 second period, measured in 100 μl assay mixture containing 40 pmol ATP and 15 nmol luciferin in Tris-glycine buffer, pH 7.6, using a GloMax 20/20 Luminometer.

Unit Definition Conversion Factor: There are approximately 9000 Relative Light Units (RLU) per one traditional Light Unit that uses a peak height equivalent to 0.02 μCi of ¹⁴C in a PPO/POPOP cocktail.