Definition of "luciferin" [lu•cif•er•in]

• A chemical substance present in the cells of bioluminescent organisms, such as fireflies, that produces an almost heatless, bluish-green light when oxidized under the catalytic effects of luciferase and ATP. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "He told me that luciferin is extremely unstable and rapidly decomposes in the presence of oxygen, and also that Professor Newton Harvey of Princeton University had been trying to purify luciferin for the past 20 years but had been unsuccessful."
• "It is produced when oxygen, breathed in through the abdominal trachea, combines with a substance called luciferin in the presence of the enzyme luciferase, in special cells called photocytes."
• "This enzyme uses ATP to power a chemical reaction in which a chemical (called luciferin) is oxidized, emitting a photon in the process."