Coelenterazine-dependent luciferase and photoprotein (CTZ-luciferase)

Coelenterazine-dependent luciferases and photoproteins represent a specialized class of bioluminescent enzymes and proteins primarily sourced from marine organisms such as Renilla reniformis, Gaussia princeps, and Aequorea victoria (Shimomura, 2006). These proteins facilitate the oxidative decarboxylation of coelenterazine, an imidazopyrazinone derivative, resulting in the emission of blue light without the requirement for adenosine triphosphate (ATP) (Markova et al., 2019). Photoproteins like aequorin are distinct in that they form a stable enzyme-substrate complex with oxygen, which triggers light emission only upon the binding of calcium ions, serving as a sensitive indicator for intracellular calcium signaling (UniProt Consortium, 2023). While these proteins are not therapeutic targets for disease intervention, they are indispensable in the pharmaceutical industry as reporter systems for high-throughput screening, gene expression analysis, and monitoring protein-protein interactions via Bioluminescence Resonance Energy Transfer (BRET) (Kim et al., 2011). In preclinical research, they enable the real-time visualization of biological processes, such as tumor progression and viral spread, in living subjects (Markova et al., 2019). Challenges associated with their use include the limited penetration of blue light through mammalian tissues, the potential immunogenicity of these non-mammalian proteins, and the pharmacokinetic limitations of the coelenterazine substrate (Kim et al., 2011). Despite these hurdles, they remain a cornerstone of modern molecular biology and drug discovery assays due to their high sensitivity and low background signal (Markova et al., 2019).

Other names

Renilla-type luciferaseGaussia-type luciferaseAequorin-like photoproteinImidazopyrazinone-dependent luciferaseRenilla luciferaseGaussia luciferaseAequorinObelin

Catalytic oxidation of the substrate coelenterazine into coelenteramide, resulting in the emission of blue light (approx. 460-480 nm); photoproteins specifically require calcium ion binding to trigger this reaction from a pre-formed peroxycoelenterazine intermediate (Markova et al., 2019; Shimomura, 2006).