The roles of the two highly unstable components F and P involved in the bioluminescence of euphausiid shrimps

• Published in: Journal of Bioluminescence and Chemiluminescence
• Main Author: Shimomura, Osamu
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1995
• Subjects: Meganyctiphanes norvegica
• Online Access: http://dx.doi.org/10.1002/bio.1170100205; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fbio.1170100205; https://onlinelibrary.wiley.com/doi/pdf/10.1002/bio.1170100205

Abstract Bioluminescence of euphausiids takes place when a fluorescent tetrapyrrole F and a highly unstable protein P react in the presence of oxygen. A previous study on the euphausiid Meganyctiphanes norvegica indicated that F acts as a catalyst and P is consumed in the luminescence reaction, differing from the luminescence system of dinoflagellates in which a tetrapyrrole luciferin, nearly identical to F, is enzymatically oxidized in the presence of dinoflagellate luciferase. In the present study, P was extracted from Euphausia pacifica as well as from M. norvegica , then purified separately by affinity chromatography on a column of biliverdin–Sepharose 4B, completing the whole process in less than 5h. The samples of P obtained from both species had a molecular weight of 600,000, a purity of about 80%, and a specific activity 50–100 times greater than that previously found. The activity of P rapidly decreased in solutions, even at 0°C, and the inactivation of P derived from M. norvegica was more than four times faster than that derived from E. pacifica . The kinetics of the luminescence reaction was investigated with F and P whose concentrations were systematically varied. The reaction was characteristically slow and involved two different reaction rates; the turnover number at 0°C was 30/h for the initial 20 min and 20/h after the initial 1 h. The total light emitted in a 50‐h period indicated that the bioluminescence quantum yield of F was about 0.6 at 0°C, and P recycled many times in the luminescence reaction. Thus, the present results conclusively show that F is a luciferin and P is a luciferase of an unusually slow‐working type, contrary to early report.