Protein nitration by polluted air

The effects of air pollution on allergic diseases are not yet well-understood. Here, we show that proteins, in particular birch pollen proteins including the allergen Bet v 1, are efficiently nitrated by polluted air. This posttranslational modification of proteins is likely to trigger immune reactions and provides a molecular rationale for the promotion of allergies by traffic-related air pollution. Enzyme immunoassays have been used to determine equivalent degrees of nitration (EDN) for protein samples exposed to urban outdoor air and synthetic gas mixtures. The observed rates of nitration were governed by the abundance of nitrogen oxides and ozone, and concentration levels typical for summer smog conditions led to substantial nitration within a few hours to days (EDN up to 20%). Moreover, nitrated proteins were detected in urban road dust, window dust, and fine air particulate matter (EDN up to 0.1%).