Luminescence spectra, Fluorescence, Luciferin

Fig. 1.5 Fluorescence emission spectrum of the luciferase-oxyluciferin complex in the same solution as in Fig. 1.4 (solid line), compared with the luminescence spectrum of firefly luciferin measured in glycylglycine buffer, pH 7.6 (dotted line). The former curve from Gates and DeLuca, 1975 the latter from Selinger and McElroy, 1960, both with permission from Elsevier.

Fig. 6.1.5 Fluorescence spectra of the purple protein (1-4) and the luminescence spectrum measured with Latia luciferin, luciferase and the purple protein (5 Xmax 536 nm). Excitation spectra (1) and (2) were measured with emission at 630 nm and 565 nm, respectively. Emission spectra (3) and (4) were measured with excitation at 285 nm and 380 nm, respectively. From Shimomura and Johnson, 1968c, with permission from the American Chemical Society.

Harvey (1952) demonstrated the luciferin-luciferase reaction with O. phosphorea collected at Nanaimo, British Columbia, Canada, and with O. enopla from Bermuda. McElroy (1960) partially purified the luciferin, and found that the luminescence spectrum of the luciferin-luciferase reaction of O. enopla is identical to the fluorescence spectrum of the luciferin (A.max 510 nm), and also that the luciferin is auto-oxidized by molecular oxygen without light emission. Further investigation on the bioluminescence of Odontosyllis has been made by Shimomura etal. (1963d, 1964) and Trainor (1979). Although the phenomenon is well known, the chemical structure of the luciferin and the mechanism of the luminescence reaction have not been elucidated. 

Oxyluciferin. During the luminescence reaction catalyzed by luciferase, luciferin is converted into a fluorescent compound, oxyluciferin, accompanied by the emission of greenish-blue light that spectrally matches the fluorescence of oxyluciferin (Fig. 7.2.6). The absorption spectrum of oxyluciferin is shown in Figs. 7.2.1 and 7.2.2. 

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