Sandbox Reserved 993: Difference between revisions
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It was believed that the chemically produced excited states stemmed from dioxetanone. This idea was proposed based on a common type of chemiluminescence which required O<sub>2</sub> at certain points in which dioxetanone is a precursor to the excited state. De Luca and colleagues did a study that proposed that the dioxetanone mechanism for bio- and chemiluminescence were false. Their experiment used oxygen isotopes and concluded that the oxygen atoms that the produced carbon dioxide consisted of did not stem from the consumed oxygen. This study, however, has been analyzed and several flaws have been discovered such as, incomplete chain of events and no proof of CO<sub>2</sub> collection from the reaction was obtainable. It was stated that the CO<sub>2</sub> produced was pumped directly out of the reaction. This was not possible due to the high reaction rate of CO<sub>2</sub> and tert-butoxide ion and the stability of monoalkyl carbonates. Johnson and Shimomura determined that an oxygen atom that makes up the CO<sub>2</sub> does indeed stem from the O<sub>2</sub> consumed by the reaction in firefly bioluminescence. De Luca and colleagues reevaluated their work and their results agreed with Johnson and Shimomura. Therefore, the dioxetane-dioxetanone mechanism for firefly bioluminescence and chemiluminescence is supported.<ref name=White1980>White, E. H., Steinmetz, M. G., Miano, J. D., Wildes, P. D. and Morland, R. (1980) "Chemi- and bioluminescence of firefly luciferin", J. Am. Chem. Soc. 102(9): 3199-3208.</ref> | It was believed that the chemically produced excited states stemmed from dioxetanone. This idea was proposed based on a common type of chemiluminescence which required O<sub>2</sub> at certain points in which dioxetanone is a precursor to the excited state. De Luca and colleagues did a study that proposed that the dioxetanone mechanism for bio- and chemiluminescence were false. Their experiment used oxygen isotopes and concluded that the oxygen atoms that the produced carbon dioxide consisted of did not stem from the consumed oxygen. This study, however, has been analyzed and several flaws have been discovered such as, incomplete chain of events and no proof of CO<sub>2</sub> collection from the reaction was obtainable. It was stated that the CO<sub>2</sub> produced was pumped directly out of the reaction. This was not possible due to the high reaction rate of CO<sub>2</sub> and tert-butoxide ion and the stability of monoalkyl carbonates. Johnson and Shimomura determined that an oxygen atom that makes up the CO<sub>2</sub> does indeed stem from the O<sub>2</sub> consumed by the reaction in firefly bioluminescence. De Luca and colleagues reevaluated their work and their results agreed with Johnson and Shimomura. Therefore, the dioxetane-dioxetanone mechanism for firefly bioluminescence and chemiluminescence is supported.<ref name=White1980>White, E. H., Steinmetz, M. G., Miano, J. D., Wildes, P. D. and Morland, R. (1980) "Chemi- and bioluminescence of firefly luciferin", J. Am. Chem. Soc. 102(9): 3199-3208.</ref> | ||
Step | Step 1: In the ''Photinus pyralis'' luciferase, the reaction begins with luciferin. Luciferase catalyzes ATP and magnesium ion to produce luciferyl AMP from luciferin. | ||
Step 2: Luciferase then catalyzes O<sub>2</sub>, producing light and oxyluciferin from Luciferyl AMP. <ref name=Thorne2012>Thorne, N., Shen, M., Lea, W. A., Simeonov, A., Lovell, S., Auld, D. S. and Inglese, J. (2012) "Firefly luciferase in chemical biology: A compendium of inhibitor, mechanistic evaluation of chemotypes, and suggested use as a reporter", Chem. Biol. 19(8): 1060-1072. doi:http://dx.doi.org/10.1016%2Fj.chembiol.2012.07.015</ref><ref name=White1980 /> | Step 2: Luciferase then catalyzes O<sub>2</sub>, producing light and oxyluciferin from Luciferyl AMP.<ref name=Thorne2012>Thorne, N., Shen, M., Lea, W. A., Simeonov, A., Lovell, S., Auld, D. S. and Inglese, J. (2012) "Firefly luciferase in chemical biology: A compendium of inhibitor, mechanistic evaluation of chemotypes, and suggested use as a reporter", Chem. Biol. 19(8): 1060-1072. doi:http://dx.doi.org/10.1016%2Fj.chembiol.2012.07.015</ref><ref name=White1980 /> | ||
[[Image:Luciferase_Mechanism_Without_Spelling_Errors.jpg]] | [[Image:Luciferase_Mechanism_Without_Spelling_Errors.jpg]] | ||
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== Function == | == Function == | ||
There are three main functions of bioluminescence in nature: offense, defense and communication. Offense suggests baiting or enticing prey, defense suggests camouflage or protection and communication relates to courtship and mating. The literature suggests that the firefly species mainly use bioluminescence for communication purposes.<ref name=Greer2002> Greer, L.F., and Szalay, A.A. (2002). “Imaging of Light Emission from the Expression of Luciferases in Living Cells and Organisms: A Reivew.” Luminescence 17(1):43-74. doi: 10.1002/bio.676. </ref> | There are three main functions of bioluminescence in nature: offense, defense and communication. Offense suggests baiting or enticing prey, defense suggests camouflage or protection and communication relates to courtship and mating. The literature suggests that the firefly species mainly use bioluminescence for communication purposes.<ref name=Greer2002> Greer, L.F., and Szalay, A.A. (2002). “Imaging of Light Emission from the Expression of Luciferases in Living Cells and Organisms: A Reivew.” Luminescence 17(1):43-74. doi: 10.1002/bio.676.</ref> | ||
Firefly communication was discussed in more detail in a video produced by Science Friday featuring James Llyod and Marc Branham of the University of Florida, Gainsville. | Firefly communication was discussed in more detail in a video produced by Science Friday featuring James Llyod and Marc Branham of the University of Florida, Gainsville. [https://www.youtube.com/watch?v=RpywSqvXDqc] | ||
Some regions of the luciferase sequence conservation are found in acyl-CoA ligases and a family of peptide synthases, suggesting they may have a similar secondary function. Acyl-CoA ligases are found to activate many different substrates, ultimately transferring them to a thiol group of CoA. In eukaryotes, this mechanism can be found in the activation step of fatty acids either for the synthesis of cellular lipids or for fatty acid degradation via beta-oxidation. The family of peptide ligases that contain sequence similarities have been found to participate in antibiotic synthesis in microorganisms. <ref name=Conti1996 /> | Some regions of the luciferase sequence conservation are found in acyl-CoA ligases and a family of peptide synthases, suggesting they may have a similar secondary function. Acyl-CoA ligases are found to activate many different substrates, ultimately transferring them to a thiol group of CoA. In eukaryotes, this mechanism can be found in the activation step of fatty acids either for the synthesis of cellular lipids or for fatty acid degradation via beta-oxidation. The family of peptide ligases that contain sequence similarities have been found to participate in antibiotic synthesis in microorganisms. <ref name=Conti1996 /> | ||