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Excited singlet molecular O₂(¹Δg) is generated enzymatically from excited carbonyls in the dark.
Sci Rep 2014; 4:5938SR

Abstract

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 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)Δg). Indirect analysis of O2 ((1)Δg) 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)Σg(-))], chemical trapping of (18)O2 ((1)Δg) 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)Δg). Altogether, photoemission and chemical trapping studies clearly demonstrate that chemically and enzymatically nascent excited carbonyl generates (18)O2 ((1)Δg) by triplet-triplet energy transfer to ground state oxygen O2 ((3)Σg(-)), and supports the long formulated hypothesis of O2 ((1)Δg) involvement in physiological and pathophysiological events that might take place in tissues in the absence of light.

Authors+Show Affiliations

Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, CEP 05513-970, CP 26077, São Paulo, SP, Brazil.Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, CEP 05513-970, CP 26077, São Paulo, SP, Brazil.Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, CEP 05513-970, CP 26077, São Paulo, SP, Brazil.Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, CEP 05513-970, CP 26077, São Paulo, SP, Brazil.Departamento de Bioquímica e Biologia Molecular, Setor de Ciências Biológicas, Universidade Federal do Paraná, Curitiba, PR, Brazil.Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, CEP 05513-970, CP 26077, São Paulo, SP, Brazil.Institut Nanosciences et Cryogénie, CEA/Grenoble, F-38054 Grenoble Cedex 9, France.Institute of Biochemistry and Molecular Biology I, and Leibniz Research Institute for Environmental Medicine, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany.Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, CEP 05513-970, CP 26077, São Paulo, SP, Brazil.1] Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, CEP 05513-970, CP 26077, São Paulo, SP, Brazil [2] Departamento de Ciências Exatas e da Terra, Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, SP, Brazil.Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, CEP 05513-970, CP 26077, São Paulo, SP, Brazil.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

25087485

Citation

Mano, Camila M., et al. "Excited Singlet Molecular O₂(¹Δg) Is Generated Enzymatically From Excited Carbonyls in the Dark." Scientific Reports, vol. 4, 2014, p. 5938.
Mano CM, Prado FM, Massari J, et al. Excited singlet molecular O₂(¹Δg) is generated enzymatically from excited carbonyls in the dark. Sci Rep. 2014;4:5938.
Mano, C. M., Prado, F. M., Massari, J., Ronsein, G. E., Martinez, G. R., Miyamoto, S., ... Di Mascio, P. (2014). Excited singlet molecular O₂(¹Δg) is generated enzymatically from excited carbonyls in the dark. Scientific Reports, 4, p. 5938. doi:10.1038/srep05938.
Mano CM, et al. Excited Singlet Molecular O₂(¹Δg) Is Generated Enzymatically From Excited Carbonyls in the Dark. Sci Rep. 2014 Aug 4;4:5938. PubMed PMID: 25087485.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Excited singlet molecular O₂(¹Δg) is generated enzymatically from excited carbonyls in the dark. AU - Mano,Camila M, AU - Prado,Fernanda M, AU - Massari,Júlio, AU - Ronsein,Graziella E, AU - Martinez,Glaucia R, AU - Miyamoto,Sayuri, AU - Cadet,Jean, AU - Sies,Helmut, AU - Medeiros,Marisa H G, AU - Bechara,Etelvino J H, AU - Di Mascio,Paolo, Y1 - 2014/08/04/ PY - 2014/06/09/received PY - 2014/07/16/accepted PY - 2014/8/5/entrez PY - 2014/8/5/pubmed PY - 2015/10/27/medline SP - 5938 EP - 5938 JF - Scientific reports JO - Sci Rep VL - 4 N2 - 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 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)Δg). Indirect analysis of O2 ((1)Δg) 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)Σg(-))], chemical trapping of (18)O2 ((1)Δg) 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)Δg). Altogether, photoemission and chemical trapping studies clearly demonstrate that chemically and enzymatically nascent excited carbonyl generates (18)O2 ((1)Δg) by triplet-triplet energy transfer to ground state oxygen O2 ((3)Σg(-)), and supports the long formulated hypothesis of O2 ((1)Δg) involvement in physiological and pathophysiological events that might take place in tissues in the absence of light. SN - 2045-2322 UR - https://www.unboundmedicine.com/medline/citation/25087485/Excited_singlet_molecular_O₂_¹Δg__is_generated_enzymatically_from_excited_carbonyls_in_the_dark_ L2 - http://dx.doi.org/10.1038/srep05938 DB - PRIME DP - Unbound Medicine ER -