Theoretically obtained insight into the mechanism and dioxetanone species responsible for the singlet chemiexcitation of Coelenterazine

Min, Chungang; Ferreira, Paulo J.O.; Silva, Luís Pinto da

doi:10.1016/j.jphotobiol.2017.07.012

Cited by 27 publications

(59 citation statements)

References 77 publications

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“…However, theoretical and experimental studies indicated the possible involvement of neutral dioxetanones in efficient chemiexcitation, instead of anionic species [26][27][28][29][30]. More specifically, theoretical calculations made by our team revealed seemingly more beneficial chemiexcitation profiles [26,29,30]. In turn, Hirano et al [27] performed an experimental and theoretical study of the chemiluminescence of Cypridina analogues and stated that the reaction mechanism of the chemiluminescence of neutral species should explain the highly efficient chemiexcitation of Cypridina bioluminescence.…”

Section: Introductionmentioning

confidence: 86%

“…From this resulted the Charge Transfer-Initiated Luminescence (CTIL) mechanism [24,25]. However, theoretical and experimental studies indicated the possible involvement of neutral dioxetanones in efficient chemiexcitation, instead of anionic species [26][27][28][29][30]. More specifically, theoretical calculations made by our team revealed seemingly more beneficial chemiexcitation profiles [26,29,30].…”

Section: Introductionmentioning

confidence: 91%

“…In fact, they stated that the CIEEL and CTIL mechanisms are not applicable for explaining the high singlet chemiexcitation yield in aequorin bioluminescence [28]. Furthermore, an analysis of different systems indicated that there was no clear relationship between CT/BCT and efficient singlet chemiexcitation, as some dioxetanones presented similar chemiexcitation profiles, despite their decomposition occurring with relevant differences in terms of CT/BCT [26,[29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

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Tuning the Intramolecular Chemiexcitation of Neutral Dioxetanones by Interaction with Ionic Species

Magalhães

Silva

2022

Molecules

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The intramolecular chemiexcitation of high-energy peroxide intermediates, such as dioxetanones, is an essential step in different chemi- and bioluminescent reactions. Here, we employed the Time-Dependent Density Functional Theory (TD-DFT) methodology to evaluate if and how external stimuli tune the intramolecular chemiexcitation of model dioxetanones. More specifically, we evaluated whether the strategic placement of ionic species near a neutral dioxetanone model could tune its thermolysis and chemiexcitation profile. We found that these ionic species allow for the “dark” catalysis of the thermolysis reaction by reducing the activation barrier to values low enough to be compatible with efficient chemi- and bioluminescent reactions. Furthermore, while the inclusion of these species negatively affected the chemiexcitation profile compared with neutral dioxetanones, these profiles appear to be at least as efficient as anionic dioxetanones. Thus, our results demonstrated that the intramolecular chemiexcitation of neutral dioxetanones can be tuned by external stimuli in such a way that their activation barriers are decreased. Thus, these results could help to reconcile findings that neutral dioxetanones could be responsible for efficient chemi-/bioluminescence, while being typically associated with high activation parameters.

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Section: Introductionmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

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Tuning the Intramolecular Chemiexcitation of Neutral Dioxetanones by Interaction with Ionic Species

Magalhães

Silva

2022

Molecules

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“…DFT and CASSCF/CASPT2 [49][50][51] methods were used herein as implemented in the Gaussian 09 [52] and MOLCAS 8 [53] programs, respectively,t od ecipher the molecular basis of the chemiluminescence mechanism of LH 2 .A ll computations were carried out by imposing no restrictions on the symmetry of the molecule (C 1 symmetry) The long-range corrected BLYP functional (LC-BLYP) [54][55][56][57] was used with the 6-31G* basis set, hereafter LC-BLYP/6-31G*, to determine the minima and TSs for the L 2À + 3 O 2 !CP 2À reaction step. The openshell approach, as established in previous studies, [33,[58][59][60][61][62] was used to correctly determine the geometries and energies of the singlet biradical structures. The reaction vector at the TS was analyzed to confirm connectivity between reactants and products.…”

Section: Computational Detailsmentioning

confidence: 99%

Molecular Basis of the Chemiluminescence Mechanism of Luminol

Giussani

Farahani

Martínez‐Muñoz

et al. 2019

Chemistry A European J

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Light emission from luminol is probably one of the most popular chemiluminescence reactions due to its use in forensic science, and has recently displayed promising applications for the treatment of cancer in deep tissues. The mechanism is, however, very complex and distinct possibilities have been proposed. By efficiently combining DFT and CASPT2 methodologies, the chemiluminescence mechanism has been studied in three steps: 1) luminol oxygenation to generate the chemiluminophore, 2) a chemiexcitation step, and 3) generation of the light emitter. The findings demonstrate that the luminol double‐deprotonated dianion activates molecular oxygen, diazaquinone is not formed, and the chemiluminophore is formed through the concerted addition of oxygen and concerted elimination of nitrogen. The peroxide bond, in comparison to other isoelectronic chemical functionalities (−NH−NH−, −N−−N−−, and −S−S−), is found to have the best chemiexcitation efficiency, which allows the oxygenation requirement to be rationalized and establishes general design principles for the chemiluminescence efficiency. Electron transfer from the aniline ring to the OO bond promotes the excitation process to create an excited state that is not the chemiluminescent species. To produce the light emitter, proton transfer between the amino and carbonyl groups must occur; this requires highly localized vibrational energy during chemiexcitation.

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“…not a “full” electron, may be sufficient to trigger the decomposition of the peroxide and subsequently leads to the generation of an excited state [ [77] , [78] , [79] , [80] ]. Although most theoretical studies in the field of bioluminescence have focused on the firefly [ [78] , [79] , [80] ] and Cypridina bioluminescence [ 81 , 82 ], it is conceivable that an equivalent charge-transfer process occurs in the bacterial bioluminescent reaction. Taking this into consideration, the mechanism depicted in Scheme 5 (top) represents the extreme case of a “full” electron transfer but may in fact only involve the transfer of charge from the flavin to the peroxide bond to trigger the events leading to the generation of the excited state FMN-4a-hydroxide.…”

Section: Structure-function Relationshipsmentioning

confidence: 99%

Molecular Mechanisms of Bacterial Bioluminescence

Brodl

Winkler

Macheroux

2018

Computational and Structural Biotechnology Journal

116

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Bioluminescence refers to the production of light by living organisms. Bioluminescent bacteria with a variety of bioluminescence emission characteristics have been identified in Vibrionaceae, Shewanellaceae and Enterobacteriaceae. Bioluminescent bacteria are mainly found in marine habitats and they are either free-floating, sessile or have specialized to live in symbiosis with other marine organisms. On the molecular level, bioluminescence is enabled by a cascade of chemical reactions catalyzed by enzymes encoded by the lux operon with the gene order luxCDABEG. The luxA and luxB genes encode the α- and β- subunits, respectively, of the enzyme luciferase producing the light emitting species. LuxC, luxD and luxE constitute the fatty acid reductase complex, responsible for the synthesis of the long-chain aldehyde substrate and luxG encodes a flavin reductase. In bacteria, the heterodimeric luciferase catalyzes the monooxygenation of long-chain aliphatic aldehydes to the corresponding acids utilizing reduced FMN and molecular oxygen. The energy released as a photon results from an excited state flavin-4a-hydroxide, emitting light centered around 490 nm. Advances in the mechanistic understanding of bacterial bioluminescence have been spurred by the structural characterization of protein encoded by the lux operon. However, the number of available crystal structures is limited to LuxAB (Vibrio harveyi), LuxD (Vibrio harveyi) and LuxF (Photobacterium leiognathi). Based on the crystal structure of LuxD and homology models of LuxC and LuxE, we provide a hypothetical model of the overall structure of the LuxCDE fatty acid reductase complex that is in line with biochemical observations.

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Theoretically obtained insight into the mechanism and dioxetanone species responsible for the singlet chemiexcitation of Coelenterazine

Cited by 27 publications

References 77 publications

Tuning the Intramolecular Chemiexcitation of Neutral Dioxetanones by Interaction with Ionic Species

Tuning the Intramolecular Chemiexcitation of Neutral Dioxetanones by Interaction with Ionic Species

Molecular Basis of the Chemiluminescence Mechanism of Luminol

Molecular Mechanisms of Bacterial Bioluminescence

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