Coelenterazine 400a

Coelenterazine 400a (CAS No.: 70217-82-2) is a synthetic derivative of coelenterazine that functions as a substrate for Renilla luciferase, enabling bioluminescent signal generation through enzymatic oxidation and emitting blue light with a peak around 395 nm. As a modified analog, it alters the electronic properties of the luciferase-catalyzed reaction via substitution within the methylene bridge, resulting in a shifted emission spectrum and improved signal discrimination compared to other coelenterazine variants. This spectral characteristic underpins its widespread application in bioluminescence resonance energy transfer (BRET 2) assays, where it is commonly paired with compatible fluorescent protein acceptors such as GFP variants to study protein–protein interactions and signaling dynamics, including pathways associated with G protein-coupled receptors. Coelenterazine 400a is broadly utilized in cell-based reporter systems and live-cell imaging platforms, where it supports high-sensitivity detection and enhanced resolution of molecular interactions. While specific potency metrics are not typically defined for luciferase substrates, experimental use generally falls within nanomolar to micromolar concentration ranges depending on assay configuration, cell type, and detection requirements, making it a valuable tool in mechanistic studies, high-throughput screening, and drug discovery workflows involving bioluminescent readouts.