Heterogeneous Reaction of Protein Samples with Ambient Urban Air: Ratio of Nitration and Oligomerization Products
Rachel L. Davey, Alyssa Knaus, Paola Gascot, ALEKSANDRA VOLKOVA, Erick Mattson, J. Alex Huffman,
University of Denver Abstract Number: 549
Working Group: Aerosol Chemistry
AbstractAmbient air pollutants like ozone (O
3) and nitrogen dioxide (NO
2) can act as reactive oxygen species (ROS) and reactive nitrogen species (RNS) to chemically react with proteins in the atmosphere. Such post-translational modifications (PTMs) may promote changes in physiological response upon inhalation and on biological surfaces. For example, the observed increase in allergic disease, including allergic rhinitis and asthma, has been hypothesized to have a link to the reaction of allergens with ROS/RNS in the atmosphere. Nitration (NTyr) is a PTM that forms via the reaction with O
3 and NO
2 and has been shown to exacerbate the allergenic potential in rat models. NTyr formation also competes with oligomerization (dityrosine cross-linking, DiTyr), which has also been shown to form in the presence of O
3. We previously reported preliminary results showing the nitration of bovine serum albumin (BSA) in ambient air via O
3 and NO
2. Here we present more extensive results correlating NTyr and DiTyr formation to concentrations of O
3 and ROS observed at sites in the urban and suburban vicinity of Denver, Colorado, which is among the most a highly O
3 polluted regions in the United States. Nitration degree values up to 5.5% were observed, compared to oligomerization degrees of 56.1%, showing the oligomerization pathways as atmospherically significant. The ratio of NTyr to DiTyr was also observed to scale with the O
3 and ROS concentrations, suggesting that the reaction products on bioaerosol surfaces and at the atmosphere-biosphere interface will vary, depending on geography and atmospheric conditions.