Radical formation in the gas-phase ozonolysis of deprotonated cysteine

Khairallah, George N., Maccarone, Alan T., Pham, Huong T., Benton, Timothy M., Ly, Tony, da Silva, Gabriel, Blanksby, Stephen J., & O'Hair, Richard A.J. (2015) Radical formation in the gas-phase ozonolysis of deprotonated cysteine. Angewandte Chemie (International Edition), 54(44), pp. 12947-12951.

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Abstract

Although the deleterious effects of ozone on the human respiratory system are well-known, many of the precise chemical mechanisms that both cause damage and afford protection in the pulmonary epithelial lining fluid are poorly understood. As a key first step to elucidating the intrinsic reactivity of ozone with proteins, its reactions with deprotonated cysteine [Cys-H]- are examined in the gas phase. Reaction proceeds at near the collision limit to give a rich set of products including 1) sequential oxygen atom abstraction reactions to yield cysteine sulfenate, sulfinate and sulfonate anions, and significantly 2) sulfenate radical anions formed by ejection of a hydroperoxy radical. The free-radical pathway occurs only when both thiol and carboxylate moieties are available, implicating electron-transfer as a key step in this reaction. This novel and facile reaction is also observed in small cys-containing peptides indicating a possible role for this chemistry in protein ozonolysis. Gas-phase reactions: Deprotonated cysteine reacted with ozone to give a rich set of products including sequential oxygen atom abstraction reactions to yield cysteine sulfenate, sulfonate, and sulfonate anions, and significantly sulfenate radical anions formed by ejection of a hydroperoxy radical (see picture). The free-radical pathway occurred only when both thiol and carboxylate moieties were available.

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ID Code: 96427
Item Type: Journal Article
Refereed: Yes
Keywords: cysteine, gas-phase reactions, mass spectrometry, ozone, radicals, Abstracting, Amino acids, Carboxylation, Chemical reactions, Free radicals, Gases, Ions, Mass spectrometry, Ozone, Phase interfaces, Proteins, Respiratory system, cysteine, Deleterious effects, Epithelial lining fluids, Gas-phase ozonolysis, Gas-phase reactions, Human respiratory system, Intrinsic reactivity, radicals, Free radical reactions
DOI: 10.1002/anie.201506019
ISSN: 1433-7851
Subjects: Australian and New Zealand Standard Research Classification > CHEMICAL SCIENCE (030000) > PHYSICAL CHEMISTRY (INCL. STRUCTURAL) (030600)
Divisions: Current > Schools > School of Chemistry, Physics & Mechanical Engineering
Current > Institutes > Institute for Future Environments
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Funding:
Copyright Owner: Copyright 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Deposited On: 30 Jun 2016 04:54
Last Modified: 03 Oct 2016 05:14

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