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

TY - JOUR

T1 - Radical formation in the gas-phase ozonolysis of deprotonated cysteine.

AU - Khairallah, George N.

AU - Maccarone, Alan T.

AU - Pham, Huong T.

AU - Benton, Timothy M.

AU - Ly, Tony

AU - da Silva , Gabriel

AU - Blanksby, Stephen J.

AU - O'Hair, Richard A. J.

PY - 2015/10/26

Y1 - 2015/10/26

N2 - 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.

AB - 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.

UR - http://europepmc.org/abstract/med/26480331

U2 - 10.1002/anie.201506019

DO - 10.1002/anie.201506019

M3 - Article

C2 - 26480331

SN - 1433-7851

VL - 54

SP - 12947

EP - 12951

JO - Angewandte Chemie International Edition

JF - Angewandte Chemie International Edition

IS - 44

ER -