Excited singlet molecular O-2 ((1)Delta g) is generated enzymatically from excited carbonyls in the dark

Author(s):Show less -

Mano, Camila M. ^[1] ; Prado, Fernanda M. ^[1] ; Massari, Julio ^[1] ; Ronsein, Graziella E. ^[1] ; Martinez, Glaucia R. ^[2] ; Miyamoto, Sayuri ^[1] ; Cadet, Jean ^[3] ; Sies, Helmut ^{[4, 5]} ; Medeiros, Marisa H. G. ^[1] ; Bechara, Etelvino J. H. ^{[1, 6]} ; Di Mascio, Paolo ^[1]

Affiliation

^[1] Univ Sao Paulo, Inst Quim, Dept Bioquim, BR-05513970 Sao Paulo - Brazil

^[2] Univ Fed Parana, Dept Bioquim & Biol Mol, Set Ciencias Biol, BR-80060000 Curitiba, Parana - Brazil

^[3] CEA Grenoble, Inst Nanosci & Cryogenie, F-38054 Grenoble 9 - France

^[4] Univ Dusseldorf, Inst Biochem & Mol Biol 1, Dusseldorf - Germany

^[5] Univ Dusseldorf, Leibniz Res Inst Environm Med, Dusseldorf - Germany

^[6] Univ Fed Sao Paulo, Inst Ciencias Ambientais Quim & Farmaceut, Dept Ciencias Exatas & Terra, Sao Paulo - Brazil

• Document type: Journal article
• Source: SCIENTIFIC REPORTS; v. 4, AUG 4 2014.
• Web of Science Citations: 23

Abstract

In mammalian tissues, ultraweak chemiluminescence arising from biomolecule oxidation has been attributed to the radiative deactivation of singlet molecular oxygen {[}O-2 ((1)Delta(g))] and electronically excited triplet carbonyl products involving dioxetane intermediates. Herein, we describe evidence of the generation of O-2 ((1)Delta(g)) in aqueous solution via energy transfer from excited triplet acetone. This involves thermolysis of 3,3,4,4-tetramethyl-1,2-dioxetane, a chemical source, and horseradish peroxidase-catalyzed oxidation of 2-methylpropanal, as an enzymatic source. Both sources of excited carbonyls showed characteristic light emission at 1,270 nm, directly indicative of the monomolecular decay of O-2 ((1)Delta(g)). Indirect analysis of O2 (1Dg) by electron paramagnetic resonance using the chemical trap 2,2,6,6-tetramethylpiperidine showed the formation of 2,2,6,6-tetramethylpiperidine-1-oxyl. Using {[}O-18]-labeled triplet, ground state molecular oxygen {[}O-18(2) ((3)Sigma(g) -)], chemical trapping of O-18(2) ((1)Delta(g)) with disodium salt of anthracene-9,10-diyldiethane-2,1-diyl disulfate yielding the corresponding double-{[}O-18]-labeled 9,10-endoperoxide, was detected through mass spectrometry. This corroborates formation of O-2 ((1)Delta(g)). Altogether, photoemission and chemical trapping studies clearly demonstrate that chemically and enzymatically nascent excited carbonyl generates O-18(2) ((1)Delta(g)) by triplet-triplet energy transfer to ground state oxygen O-2 ((1)Delta(g)), and supports the long formulated hypothesis of O-2 ((1)Delta(g)) involvement in physiological and pathophysiological events that might take place in tissues in the absence of light. (AU)

• FAPESP's process: 12/12663-1 - Singlet molecular oxygen and peroxides in chemical biology
• Grantee: Paolo Di Mascio
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 06/56530-4 - Carbonilic and redox stress associated with alpha-aminoketones and endogenous beta-ketoacids: mechanisms and biomarkers.
• Grantee: Etelvino José Henriques Bechara
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 13/07937-8 - Redoxome - Redox Processes in Biomedicine
• Grantee: Ohara Augusto
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC