Biogeochemistry Department, Max Planck Institute for Chemistry, PO Box 3060, 55128 Mainz, Germany.
Environ Sci Technol. 2012 Jun 19;46(12):6672-80. doi: 10.1021/es300871b. Epub 2012 May 25.
Proteins contained in pollen and other biological particles are nitrated by ozone and nitrogen dioxide in polluted air. The nitration can enhance the allergenic potential of proteins, which may contribute to the increasing prevalence of allergic diseases. The reactive uptake of NO(2) by aerosolized protein (bovine serum albumin) was investigated in an aerosol flow tube using the short-lived radioactive tracer (13)N. In the absence of O(3), the NO(2) uptake coefficient was below detection limit (γ(NO2) < 10(-6)), but with 20-160 ppb O(3) γ(NO2) increased from ~10(-6) to ~10(-4). Using the kinetic multilayer model of surface and bulk chemistry (KM-SUB), the observed time and concentration dependence can be well reproduced by a multiphase chemical mechanism involving ozone-generated reactive oxygen intermediates (ROIs), but not by NO(3) radicals formed in the gas phase. Product studies show the formation of protein dimers, suggesting that the ROIs are phenoxy radical derivatives of the amino acid tyrosine (tyrosyl radicals) which are also involved in physiological protein nitration processes. Our results imply that proteins on the surface of aerosol particles undergo rapid nitration in polluted air, while the rate of nitration in bulk material may be low depending on phase state and surface-to-volume ratio.
花粉和其他生物颗粒中的蛋白质被污染空气中的臭氧和二氧化氮硝化。硝化可以增强蛋白质的致敏潜力，这可能导致过敏疾病的患病率不断增加。使用短寿命放射性示踪剂 (13)N 在气溶胶流管中研究了气溶胶化蛋白质（牛血清白蛋白）对 NO(2)的反应性吸收。在没有 O(3)的情况下，NO(2)吸收系数低于检测限 (γ(NO2) < 10(-6))，但在 20-160 ppb O(3)存在下，γ(NO2)从10(-6)增加到10(-4)。使用表面和体相化学的动力学多层模型 (KM-SUB)，可以通过涉及臭氧生成的活性氧中间体 (ROIs)的多相化学反应机制很好地再现观察到的时间和浓度依赖性，但不能通过气相中形成的 NO(3)自由基来再现。产物研究表明形成了蛋白质二聚体，表明 ROIs 是氨基酸酪氨酸的苯氧基自由基衍生物（酪氨酸自由基），它们也参与生理蛋白质硝化过程。我们的结果表明，污染空气中气溶胶颗粒表面的蛋白质会迅速硝化，而体相材料的硝化速率可能取决于相态和表面积与体积比而较低。
