Coelenterazines are luminescent enzyme substrates for apoaequorin and Renilla luciferase. Apoaequorin is used as a calcium indicator whereas Renilla luciferase is commonly used as a reporter of transcription regulation. Coelenterazine binds apoaequorin to form an aequorin complex which emits light upon calcium binding, and can measure a broad range of calcium concentrations from ~0.1 uM to >100 uM. Renilla luciferase is widely used as a reporter protein and as a donor in bioluminescence resonance energy transfer (BRET) to study protein-protein interactions. Coelenterazines can also be used for chemiluminescent detection of superoxide anion and peroxynitrite in cells or tissues.Coelenterazine (native): Yellow solid soluble in MeOH or EtOH; Store at -20°C and protect from light; C26H21N3O3; MW: 423; [55779-48-1]. See also other Coelentrazine analogs and water-soluble Aquaphile™ Coelenterazines (native and analog h) for in vivo use.