Literature References: Photoprotein from the luminescent jellyfish Aequorea, mol wt 20,000 Da. Contains a single chromophore, coelentrazine, which emits a blue light via an intramolecular reaction when traces of Ca2+ are present. The protein is converted to apoaequorin, coelenteramide, and CO2 with the emission of light. Isolation and purification: O. Shimomura et al., J. Cell. Comp. Physiol. 59, 223 (1962). Mechanism of luminescence: O. Shimomura et al., Biochemistry 13, 3278 (1974). Verification of coelentrazine as chromophore: S. Inoue et al., Chem. Lett. 1975, 141. Characterization and properties of isoforms: O. Shimomura, Biochem. J. 234, 271 (1986); of semisynthetic aequorin: O. Shimomura et al., ibid. 251, 405 (1988); and recombinant forms: eidem, ibid. 270, 309 (1990). Crystal structure: J. F. Head et al., Nature 405, 372 (2000). Use in measurement of cellular calcium: A. Azzi, B. Chance, Biochim. Biophys. Acta 189, 141 (1969); J. M. Kendall et al., Anal. Biochem. 221, 173 (1994); M. N. Badminton et al., Exp. Cell Res. 216, 236 (1995). Review: O. Shimomura in Natural Products and Biological Activities, H. Imura et al., Eds (Elsevier Science Publishers, Amsterdam, 1986) p 33-44.
Properties: Sol in aq buffers >30 mg/ml. E1cm1% at 280 nm: 27.0; E1cm1% at 460 nm: 0.81. pI 4.2-4.9.
Use: For quantitation of free calcium in biological systems.