Study of coelenterazine luminescence: Electrostatic interactions as the controlling factor for efficient chemiexcitation

• Type: Article in International Scientific Journal
• Date: 2018

Authors

Magalhaes, CM (Author) Other; Joaquim C G E Esteves da Silva (Author) FCUP; da Silva, LP (Author) FCUP

Journal

Title: Journal of Luminescence

Vol. 199

Pages: 339-347

ISSN: 0022-2313

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 22 Citations

Scopus - 22 Citations

Other information

Authenticus ID: P-00N-SQA

DOI: 10.1016/j.jlumin.2018.03.069

Abstract (EN): Coelenterazine is a common substrate used by marine species in enzyme-catalyzed bioluminescent reactions, in which thermal energy is converted into excitation energy. Coelenterazine is also known to emit chemiluminescence, in the absence of enzymes. Moreover, the scaffold of this molecule is present in organisms of eight phyla, making it a prototypical system for marine chemi-/bioluminescence. The characterization of the chemiexcitation step responsible for light emission is essential for future applications in bioimaging, bioanalysis and biomedicine. We have found evidence to support the identification of a neutral dioxetanone intermediate as the responsible for efficient chemiexcitation. This is explained by attractive electrostatic interactions between the CO2 and Coelenteramide moieties, which allow the reacting dioxetanone to spend time in a PES region of degeneracy between singlet ground and excited states. Contrary to expected, there is no relationship between electron (ET)/charge (CT) transfer, from an electron-rich moiety to the peroxide, and efficient chemiexcitation. Thus, neither Chemically Induced Electron-Exchange Luminescence (CIEEL) nor Charge Transfer-Initiated Luminescence (CTIL) can be used to explain imidazopyrazinone-based chemi-/bioluminescence. We have also found a concentration-dependent quenching effect, more prevalent at acidic pH.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 9