title: Radical Formation in the Gas-Phase Ozonolysis of Deprotonated Cysteine.
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.
authors.affiliation: School of Chemistry and Bio21 Institute, University of Melbourne, Melbourne, Victoria 3010 (Australia).|ARC Centre of Excellence for Free Radical Chemistry and Biotechnology (Australia).
authors.forename: George N
authors.initials: GN
authors.lastname: Khairallah
authors.affiliation: School of Chemistry, University of Wollongong, New South Wales 2522 (Australia).
authors.forename: Alan T
authors.initials: AT
authors.lastname: Maccarone
authors.affiliation: School of Chemistry, University of Wollongong, New South Wales 2522 (Australia).
authors.forename: Huong T
authors.initials: HT
authors.lastname: Pham
authors.affiliation: School of Chemistry and Bio21 Institute, University of Melbourne, Melbourne, Victoria 3010 (Australia).|ARC Centre of Excellence for Free Radical Chemistry and Biotechnology (Australia).
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Benton
authors.affiliation: School of Chemistry, University of Wollongong, New South Wales 2522 (Australia).
authors.forename: Tony
authors.initials: T
authors.lastname: Ly
authors.affiliation: Department of Chemical and Biomolecular Engineering, The University of Melbourne, Melbourne, Victoria 3010 (Australia).
authors.forename: Gabriel
authors.initials: G
authors.lastname: da Silva
authors.affiliation: Central Analytical Research Facility, Queensland University of Technology, Queensland 4001 (Australia).|ARC Centre of Excellence for Free Radical Chemistry and Biotechnology (Australia).
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Blanksby
authors.affiliation: School of Chemistry and Bio21 Institute, University of Melbourne, Melbourne, Victoria 3010 (Australia). rohair@unimelb.edu.au.|ARC Centre of Excellence for Free Radical Chemistry and Biotechnology (Australia). rohair@unimelb.edu.au.
authors.forename: Richard A J
authors.initials: RA
authors.lastname: O'Hair
mesh_terms: D003545:Cysteine / Q000737:chemistry*; D005609:Free Radicals / Q000138:chemical synthesis / Q000737:chemistry; D005740:Gases / Q000737:chemistry; D015394:Molecular Structure; D010126:Ozone / Q000737:chemistry*; D011522:Protons
chemical_list: D005609:Free Radicals; D005740:Gases; D011522:Protons; D010126:Ozone; D003545:Cysteine
keywords: cysteine; gas-phase reactions; mass spectrometry; ozone; radicals