Information on EC 1.13.12.7 - firefly luciferase

The enzyme, which is found in fireflies (Lampyridae), is responsible for their biolouminescence. The reaction begins with the formation of an acid anhydride between the carboxylic group of D-firefly luciferin and AMP, with the release of diphosphate. An oxygenation follows, with release of the AMP group and formation of a very short-lived peroxide that cyclizes into a dioxetanone structure, which collapses, releasing a CO2 molecule. The spontaneous breakdown of the dioxetanone (rather than the hydrolysis of the adenylate) releases the energy (about 50 kcal/mole) that is necessary to generate the excited state of oxyluciferin. The excited luciferin then emits a photon, returning to its ground state. The enzyme has a secondary acyl-CoA ligase activity when acting on L-firefly luciferin (see EC 6.2.1.52).