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Excited singlet molecular O?(¹?g) is generated enzymatically from excited carbonyls in the dark.

ABSTRACT: In mammalian tissues, ultraweak chemiluminescence arising from biomolecule oxidation has been attributed to the radiative deactivation of singlet molecular oxygen [O2 ((1)?g)] and electronically excited triplet carbonyl products involving dioxetane intermediates. Herein, we describe evidence of the generation of O2 ((1)?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 O2 ((1)?g). Indirect analysis of O2 ((1)?g) 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 [(18)O]-labeled triplet, ground state molecular oxygen [(18)O2 ((3)?g(-))], chemical trapping of (18)O2 ((1)?g) with disodium salt of anthracene-9,10-diyldiethane-2,1-diyl disulfate yielding the corresponding double-[(18)O]-labeled 9,10-endoperoxide, was detected through mass spectrometry. This corroborates formation of O2 ((1)?g). Altogether, photoemission and chemical trapping studies clearly demonstrate that chemically and enzymatically nascent excited carbonyl generates (18)O2 ((1)?g) by triplet-triplet energy transfer to ground state oxygen O2 ((3)?g(-)), and supports the long formulated hypothesis of O2 ((1)?g) involvement in physiological and pathophysiological events that might take place in tissues in the absence of light.

SUBMITTER: Mano CM

PROVIDER: S-EPMC4120373 | biostudies-literature | 2014 Aug

REPOSITORIES: biostudies-literature

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Excited singlet molecular O₂(¹Δg) is generated enzymatically from excited carbonyls in the dark.

Mano Camila M CM Prado Fernanda M FM Massari Júlio J Ronsein Graziella E GE Martinez Glaucia R GR Miyamoto Sayuri S Cadet Jean J Sies Helmut H Medeiros Marisa H G MH Bechara Etelvino J H EJ Di Mascio Paolo P

Scientific reports 20140804

In mammalian tissues, ultraweak chemiluminescence arising from biomolecule oxidation has been attributed to the radiative deactivation of singlet molecular oxygen [O2 ((1)Δg)] and electronically excited triplet carbonyl products involving dioxetane intermediates. Herein, we describe evidence of the generation of O2 ((1)Δg) 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 peroxi ...[more]

PMID: 25087485

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Dataset Information

Excited singlet molecular O?(¹?g) is generated enzymatically from excited carbonyls in the dark.

Publications

Excited singlet molecular O₂(¹Δg) is generated enzymatically from excited carbonyls in the dark.

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