Popcorn Lung Triggers Laid Bare

Diacetyl, the molecule implicated in the disease known as popcorn lung, reacts with the amino acid arginine to form four products, according to a report (J. Agric. Food Chem., DOI: 10.1021/jf103251w). This is the first glimpse of what diacetyl-arginine adducts look like, even though diacetyl, also known as 2,3-butanedione, has been used as a biochemical tool for more than 40 years to modify arginine residues in proteins. Diacetyl has many uses in industry, but it has become infamous as a butter-flavoring ingredient thought to have sickened some workers at microwave popcorn plants. James M. Mathews and colleagues at RTI International, in collaboration with the National Institute of Environmental Health Sciences, combined N-α-acetyl-l-arginine with diacetyl and determined adduct structures with NMR and mass spectrometry (one shown, diacetyl portion in red). The products interconvert under certain conditions, they note. The mechanism of diacetyl toxicity isn’t known, so the researchers hope they can use the adducts to study the immune system’s response when lung proteins are exposed to diacetyl.