The molecular mechanism of bioluminescence in a diverse group of marine organisms is studied by a variety of techniques. The organisms emit light by an enzyme-substrate reaction in which luciferin (substrate) is oxidized by molecular oxygen, catalyzed by luciferase. In Aequorea (jellyfish), where the light emitted is due to a Ca2+ - binding protein, aequorin, structural studies are carried out by site-directed mutagenesis, 19F and 113CD NMR, and x-ray crystallography. In Vargula (crustacean), recombinant DNA techniques are employed to produce large amounts of luciferase or comparative and structural work. With Porichthys (fish), close structural analogues of Vargula luciferin, which induces bioluminescence capability in a non-luminous form of Porichthys, are synthesized to study the mechanism of the induction. In Apogon (fish), whose luciferin and luciferase are similar, if not identical, to those of Vargula, the luciferase is purified, the N-terminal amino acid sequence determined, and compared with that of Vargula for sequence homology. In Watasenia (squid) and Stenoteuthis (squid), still unidentified components of the bioluminescence reactions are isolated, purified, and characterized.
