Luciferin

D-Luciferin, notably Firefly luciferin (also beetle luciferin), is a bioluminescent substrate for the enzyme luciferase. Luciferin serves as the key component of the luciferase reporter assay, in which the transcription of an engineered luciferase gene is controlled by a promoter of interest. Light produced from the luciferase activity can be measured using a luminometer or a scintillation counter. Because luciferin catalysis requires oxygen and ATP to produce light, the luciferase-luciferin system can also be used to assay for ATP production in cell-based assays. Luciferin solutions are sensitive to light and must be stored in the dark.