luciferine

Luciferin is a term used for light-emitting substrates found in bioluminescent organisms. The most familiar example is firefly luciferin, often referred to as D-luciferin, which participates in the glow produced by many lampyrid species. In general, luciferins are not themselves highly luminescent until they are oxidized in the presence of the corresponding luciferase enzyme, ATP, magnesium ions, and molecular oxygen. The group includes several chemically distinct compounds across different organisms, and some sources may use the variant spelling luciferine.

In fireflies and related organisms, the luciferase-catalyzed reaction converts luciferin to an excited-state product that releases a photon as it returns to the ground state. This process typically requires ATP to activate the substrate, followed by oxidation with oxygen. The emitted light’s color varies by species and enzyme, with firefly systems commonly producing yellow-green light around 550 to 570 nanometers. Other bioluminescent systems, such as bacterial luciferin, involve different substrates and enzymes and often emit blue-green light near 490 nanometers.

Luciferin and its enzymatic reactions are widely used in scientific research and biotechnology. Luciferin-luciferase assays provide highly sensitive measurements of biological processes, including gene expression, cell viability, and promoter activity. Variants and related compounds have been developed to alter emission wavelength or improve imaging performance, enabling diverse applications in molecular biology, physiology, and in vivo imaging. The term luciferin is preferred in most scientific literature; luciferine is a less common or alternative spelling found in some texts.