Radical formation in the gas-phase ozonolysis of deprotonated cysteine.

George N. Khairallah, Alan T. Maccarone, Huong T. Pham, Timothy M. Benton, Tony Ly, Gabriel da Silva , Stephen J. Blanksby, Richard A. J. O'Hair (Lead / Corresponding author)

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

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.
Original languageEnglish
Pages (from-to)12947-12951
Number of pages5
JournalAngewandte Chemie International Edition
Volume54
Issue number44
DOIs
Publication statusPublished - 26 Oct 2015

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