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In the ''Photinus pyralis'' luciferase reaction 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> | In the ''Photinus pyralis'' luciferase reaction 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> | ||
Below is a schematic representation of the ''Photinus pyralis'' lucerifase reaction.<ref name=Branchini1998 /> In the first step, ''Photinus pyralis'' luciferase catalyzes the production of luciferyl-AMP from luciferin and ATP. An inorganic pyrophosphate is released in this step. In the second step, ''Photinus pyralis'' luciferase converts luciferyl-AMP and O<sub>2</sub> into oxyluciferin* and CO<sub>2</sub>.<ref name=White1980 /><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> When the excited electrons in oxyluciferin* relax, light is emitted. | Below is a schematic representation of the ''Photinus pyralis'' lucerifase reaction.<ref name=Branchini1998 /> In the first step, ''Photinus pyralis'' luciferase catalyzes the production of luciferyl-AMP from luciferin and ATP. An inorganic pyrophosphate is released in this step. As of 2010, the biosynthesis of luciferin was still undetermined; however, cysteine appears to be one of the reactants.<ref name=Inouye2010>Inouye, S. (2010) "Firefly luciferase: an adenylate-forming enzyme for multicatalytic functions", Cell. Mol. Life Sci. 67(3): 387-404. doi: 10.1007/s00018-009-0170-8</ref> In the second step, ''Photinus pyralis'' luciferase converts luciferyl-AMP and O<sub>2</sub> into oxyluciferin* and CO<sub>2</sub>.<ref name=White1980 /><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> When the excited electrons in oxyluciferin* relax, light is emitted. | ||
[[Image:Luciferin_Mechanism.jpg]] | [[Image:Luciferin_Mechanism.jpg]] | ||