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Some Radicals Don't Sleep at Night

NO3 - the most important free radical oxidant
in the night-time environment

Air quality and the effects of atmospheric pollution are of concern to us all. Recent studies have shown that there is a link between atmospheric pollution and increases in respiratory ailments, such as asthma, in both adults and children.

It has been suggested that ozone (O3) and nitrogen oxides that include NO2• may be responsible for increases in these respiratory conditions because these molecules can stimulate bronchial inflammation.

What is not generally appreciated is that when the sun sets, O3 and NO2• react to give a much more aggressive atmospheric radical – the nitrate radical (NO3•) – but there have been no studies of how this aggressive night-time species affects biomolecules. “The nitrate radical is destroyed by sunlight during the daytime”, says Dr Uta Wille, Chief Investigator on this project, “but during the night it is produced in very small quantities, but it is several thousand times more reactive than ozone or NO2•”.

The Centre research team is using used state-of-the-art instrumentation that includes fancy mass spectrommetry techniques to determine how the nitrate radical reacts with biomolecules such as amino acids and proteins. “Tyrosine, an essential amino acid, is rapidly nitrated”, remarked Duanne Sigmund, PhD student examining this chemistry, “so rapidly in fact as to be a cause for alarm. The nitrate radical may be the real culprit in many pollution mediated diseases”.

While this research programme is still in its early stages, it is already becoming clear that even the night-time environment may not be as benign as was once thought. Future work will use laser techniques to determine exactly how fast reactions that involve NO3• are and whether or not we need to take this radical seriously. This work will involve a collaboration with the research team of Professor Newcomb in the University of Illinois at Chicago (UIC).

In the meantime – let’s all work toward reducing the emissions that create these radicals in the first place!