Bioluminescence in living animals
CT-99021 mainly produced by an enzymatic reaction of a luciferase and a luciferin with molecular oxygen [1]. In marine organisms, imidazopyrazinone compounds including coelenterazine and Cypridina luciferin are known as a substrate for the luminescence reaction [2]. Coelenterazine is used in various luciferases of coelenterates (e.g. Renilla, Ptilosarcus, Periphylla), copepods (e.g. Gaussia, Metridia), decapods (e.g. Oplophorus, Systellaspis) and ostracods (e.g. Conchoecia) [3]. Cypridina luciferin is found in luminous ostracods (e.g. Cypridina, Vargula) and fishes (e.g. Porichthys) [3]. Coelenterazine is also utilized as a light emitting substrate for various Ca2+-binding photoproteins including aequorin, obelin, mitrocomin and clytin in coelenterates [4]. Of
analogous structures imidazopyrazinone-type luciferases and photoproteins, Renilla luciferase, Gaussia luciferase and aequorin have been shown to be the potential reporters both in vivo and in vitro [5], [6], [7] and [8].
