Luciferase scheme

The following schemes represent the overall reaction of firefly bioluminescence (McElroy and DeLuca, 1978), where E is luciferase LH2 is D-luciferin PP is pyrophosphate AMP is adenosine phosphate LH2-AMP is D-luciferyl adenylate (an anhydride formed between the carboxyl group of luciferin and the phosphate group of AMP) and L is oxyluciferin. 

The biochemical mechanism of bacterial luminescence has been studied in detail and reviewed by several authors (Hastings and Nealson, 1977 Ziegler and Baldwin, 1981 Lee et al., 1991 Baldwin and Ziegler, 1992 Tu and Mager, 1995). Bacterial luciferase catalyzes the oxidation of a long-chain aldehyde and FMNH2 with molecular oxygen, thus the enzyme can be viewed as a mixed function oxidase. The main steps of the luciferase-catalyzed luminescence are shown in Fig. 2.1. Many details of this scheme have been experimentally confirmed. 

The reaction scheme of Latia bioluminescence. Based on the structures of luciferin 1 (Ln) and the product of luminescence reaction 2 (OxLn), it was proposed that the luciferase-catalyzed luminescence reaction of Latia luciferin in the presence of the purple protein results in the formation of 2 moles of formic acid, as shown in the scheme A (Shimomura and Johnson, 1968c). However, when the luminescence reaction was carried out in a medium containing ascorbate and NADH (in addition to the purple protein) to increase the quantum yield, it was found that only one mole of formic acid was produced accompanied... 

Fig. 6.3.5 A reaction scheme proposed by Tsuji (2002) for the Watasenia bioluminescence. The proposed mechanism involves the adenylation of luciferase-bound luciferin by ATP, like in the bioluminescence of fireflies. However, the AMP group is split off from luciferin before the oxygenation of luciferin, differing from the mechanism of the firefly bioluminescence. Thus the role of ATP in the Watasenia bioluminescence reaction remains unclear. Reproduced with permission from Elsevier.

The preparations of luciferin (Ln, an electron acceptor) and soluble enzyme used were crude or only partially purified. The luciferase was an insoluble particulate material, possibly composed of many substances having various functions. Moreover, the luciferin-luciferase reaction was negative when both luciferin and luciferase were prepared from certain species of luminous fungus. It appears that the light production reported was the result of a complex mechanism involving unknown substances in the test mixture, and probably the crucial step of the light-emitting reaction is not represented by the above schemes. 

Bacterial bioluminescence, 30-46 factors required, 31 general scheme, 32 in vivo luminescence, 41 luminescence reaction, 37, 38 Bacterial luciferase, 33-35, 343 assay, 39 cloning, 34 crystal structure, 34 extraction and purification, 34 inactivation, 34, 35 molecular weight, 34 properties, 34 storage, 35 subunits, 34... 

Laetmogone, 301, 337 Latnpadena, 163, 339 Lampito, 216, 234, 335 Lampteroflavin, 270 Lampteromyces, 267, 270 Lampyridae, 1, 2 See also Fireflies distribution, 2 morphology, 2 Lampyris, 2, 337 Latia bioluminescence, 189 activators and inhibitors, 189 light emitter, 191 luminescence spectrum, 192 reaction scheme, 190 Latia luciferase, 183-189, 343 assay, 184... 

Figure 2 A more detailed scheme of ATP firefly luciferase reaction. LF = luciferase OL = oxiluciferine LFH2 = reduced luciferase PP = pirophosphate OL = oxiluciferine in the excited state.

Of the many types of bioluminescence in nature, that of the firefly represents the most thoroughly studied and best understood biological luminescent process. The molecular mechanism of light emission by the firefly was elucidated in the 1960s in which a dioxetanone (a-peroxy lactone) was proposed as an intermediate, formed by the luciferase-catalyzed enzymatic oxidation of the firefly luciferin with molecular oxygen (Scheme 15). This biological reaction constitutes one of the most efficient luminescent processes known to date . Hence, it is not surprising that the luciferin-luciferase system finds wide use... 

The CIEEL mechanism has been utilized to explain the catalyzed decomposition of several cyclic and linear peroxides, including diphenoyl peroxide (4), peroxyesters and 1,2-dioxetanones. Special interest has focused on this mechanism when it was utilized to explain the efficient excited state formation in the chemiexcitation step of the firefly s luciferin/luciferase bio luminescence. However, doubts have been voiced more recently about the validity of this mechanistic scheme, due to divergences about the... 

Analogously to the firefly luciferin/luciferase system, the general chemiluminescence mechanism postulated for 9-carboxyacridinium derivatives proposes the 1,2-dioxetanone 45 as high-energy intermediate However, this 1,2-dioxetanone is the only intermediate that has not yet been isolated . The cleavage of the peroxidic ring presumably results in the release of CO2 and the formation of an acridan residue in its electronically excited state (Scheme 32). 

Fig. 42. Hypothetical scheme depicting the pathways and intermediates in the luciferase-catalyzed oxidation of FMNHj by molecular oxygen. Intermediates II and Ila are in reversible equilibrium the apparent first-order rate constants for the decay of II (ka) and Ila (fcb) are similar but not identical, and they may differ considerably, depending on many factors and conditions. E, enzyme. From Hastings et al. (1973).

Fig. 17 Reaction schemes for the bioluminescence of lucifera-ses. Both forms of luciferase catalyze the oxidation of their respective substrates (A) Renilla luciferase oxidizes coelenter-azine (B) firefly luciferase oxidizes beetle luciferin.

In firefly luciferase reaction, the luminescence activity is enhanced by addition of Coenzyme A (CoA) and this phenomenon is explained by release of product inhibition. Also, firefly luciferase shows the sequence similarity to mammalian fatty acyl-CoA synthetase (AcCoAS) and plant 4-coumarate CoA ligase (4CL). They are classified as an adenylation enzyme for synthesizing acyl-CoA derivatives fi om carboxylic acid compounds in the presence of CoA, ATP and Mg (Scheme 1). Furthermore, it was reported that the luminescence activity of firefly luciferase is inhibited competitively by various long-chain fatty acids. We have determined that firefly luciferase is a bi-functional enzyme, catalyzing both the luminescence reaction and fatty acyl-CoA synthetic reaction. ... 

Proceeding from the available literary data, " the following kinetic scheme of luciferase functionality (Fig. 1) can be derived ... 

The reaction mechanism of bacterial luciferase has been studied extensively.1 2 An electron-exchange reaction mechanism (Scheme l)3 4 has been postulated and gained considerable acceptance. 

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