BIOLUMINESCENCE FROM THE REACTION OF FMN, H2O2 AND LONG CHAIN ALDEHYDE WITH BACTERIAL LUCIFERASE |
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Authors: | J. W. Hastings,,Shiao-Chun, Tu,James E.,Becvar &Dagger Robert P.,Presswood |
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Affiliation: | The Biological Laboratories, Harvard University, Cambridge, MA 02138, U.S.A;*Department of Biophysical Sciences, University of Houston, Houston, TX 77004, U.S.A. |
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Abstract: | Abstract— The bioluminescent oxidation of reduced flavin mononucleotide by bacterial luciferase involves a long-lived flavoenzyme intermediate whose chromophore has been postulated to be the 4a-sub-stituted peroxy anion of reduced flavin. Reaction of long chain aldehyde with this intermediate results in light emission and formation of the corresponding acid. These experiments show that the typical aldehyde-dependent, luciferase-catalyzed bioluminescence can also be obtained starting with FMN and H2O2 instead of FMNH2 and O2. We postulate that the 4a-peroxy anion intermediate is formed directly by attack of H2O2 on FMN. The latter may be bound to luciferase. An enzyme bound intermediate is formed which by kinetic analysis, flavin specificity for luminescence, aldehyde dependence, and bioluminescent emission spectrum appears to be identical with the species generated by reaction of FMNH, and O2 with luciferase. The quantum yield of the H2O2-- and FMN-initiated biolumlnescence is low but can be enhanced by certain metal ions, which also stimulate a chemiluminescent reaction of oxidized flavin with H2O2. The peak of this chemiluminescence. however, appears to be at a shorter wavelength than that (490 nm) of the bioluminescence. |
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