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

• Tipo: Artigo em Revista Científica Internacional
• Data: 2017

Autores

Min, CG (Autor) Outra; Ferreira, PJO (Autor) Outra; da Silva, LP (Autor) FCUP

Revista

Título: Journal of Photochemistry and Photobiology B: Biology

Vol. 174

Páginas: 18-26

ISSN: 1011-1344

Editora: Elsevier

Indexação

ISI Web of Knowledge - 26 Citações

Scopus - 27 Citações

Outras Informações

ID Authenticus: P-00N-31H

DOI: 10.1016/j.jphotobiol.2017.07.012

Abstract (EN): Coelenterazine is a widespread bioluminescent substrate for a diverse set of marine species. Moreover, its imidazopyrazinone core is present in eight phyla of bioluminescent organisms. Given their very attractive intrinsic properties, these bioluminescent systems have been used in bioimaging, photodynamic therapy of cancer, as gene reporter and in sensing applications, among others. While it is known that bioluminescence results from the thermolysis of high-energy dioxetanones, the mechanism and dioxetanone species responsible for the singlet chemiexcitation of Coelenterazine are not fully understood. The theoretical characterization of the reactions of model Coelenterazine dioxetanones showed that efficient chemiexcitation is caused by a neutral dioxetanone with limited electron and charge transfer, by accessing a region of the PES where ground and excited states are nearly-degenerated. This finding was supported by calculation of equilibrium constants, which showed that only neutral dioxetanone is present in conditions associated with bioluminescence. Moreover, while cationic amino acids easily protonate amide dioxetanone, anionic ones cannot deprotonate the neutral species. These results indicate that, contrary to existent theories, efficient chemiexcitation can occur with significant electron and/or charge transfer. In fact, these processes can be prejudicial to chemiexcitation, as anionic dioxetanones showed a less efficient chemiexcitation despite the occurrence of significant electron and charge transfer.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 9