Sandbox Reserved 993: Difference between revisions
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</StructureSection> | </StructureSection> | ||
== Mechanism == | == Mechanism == | ||
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> | ||
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The active site environment influences the wavelength of the light emitted. Single amino acid changes within the active site of ''Photinus pyralis'' luciferase can shift the luminescence from yellow-green to red. Modifying the position of the Ser314-Leu319 loop near the active site can alter Biolumanescence color. When assayed under acidic conditions, all spectra underwent a red shift while basic conditions caused a blue shift. These experiments were done using ''E. coli'' as the host organism indicating that the internal pH of the cell was close to the external pH. These findings suggest a possible use of bioluminescence in pH monitoring, biosensing and tissue and animal imaging.<ref name=Shapiro2005 /> | The active site environment influences the wavelength of the light emitted. Single amino acid changes within the active site of ''Photinus pyralis'' luciferase can shift the luminescence from yellow-green to red. Modifying the position of the Ser314-Leu319 loop near the active site can alter Biolumanescence color. When assayed under acidic conditions, all spectra underwent a red shift while basic conditions caused a blue shift. These experiments were done using ''E. coli'' as the host organism indicating that the internal pH of the cell was close to the external pH. These findings suggest a possible use of bioluminescence in pH monitoring, biosensing and tissue and animal imaging.<ref name=Shapiro2005 /> | ||
== 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/> | ||