Properties and reaction mechanism of the bioluminescence system of the deep-sea shrimp Oplophorus gracilorostris

Publisher Website
Google Scholar
Abstract
The bioluminescent reaction of Oplophorus takes place when the oxidation of coelenterazine (the luciferin) with molecular O2 is catalyzed by Oplophorus luciferase, resulting in light of maximum intensity at 462 nm and CO2 and coelenteramide products. Oplophorus luciferase was obtained in a highly purified state. Optimum luminescence occurs at pH 9 in the presence of 0.05-0.1 M NaCl at 40.degree. C and due to the unusual resistance of this enzyme to heat, visible luminescence occurs at temperatures > 50.degree. C when the highly purified enzyme is used, or at > 70.degree. C when partially purified enzyme is used. The specific activity of purest preparations is 1.75 .times. 1015 photons s-1 mg-1 at 23.degree. C. At pH 8.7, native luciferase has a MW approximately 130,000, apparently comprising 4 monomers of 31,000; at lower pH, the native luciferase tends to polymerize. The quantum yield of coelenterazine is 0.34 at 22.degree. C with this enzyme. After the luminescent reaction, the spent solution is nonfluorescent, as are solutions of luciferase alone. When the bioluminescent reaction was carried out in the presence of 18O2, the product CO2 contained > 50% C18O16O, supporting the dioxetane mechanism, but without ruling out the linear peroxide mechanism.