Of sizzling steaks and DNA repair

A pathway protects cells from mutations caused by sugar-derived aldehydes In a now famous paper for gastronomes, French physician and chemist Louis C. Maillard described in 1912 the spontaneous reaction between sugars and proteins at high temperatures ( 1 ). Sugars, often thought of as chemically inert, possess a carbonyl group (in the form of aldehydes and ketones) that, at elevated temperatures, is highly reactive toward free amine groups in proteins, ultimately forming advanced glycation end (AGE) products. The so-called “Maillard” reaction is the reason why the browning of meat reveals delicious flavors; AGE carbonyl adducts alter the aromatic and gustatory properties of biomolecules present in cooked food products. But should we care about the natural decomposition of sugars or the production of aldehydes and ketones in our bodies? As suspected by Maillard himself, the answer is an emphatic yes because carbonyls are ubiquitous and can compromise cell health. On page 208 of this issue, Richarme et al. ( 2 ) identify that an unusual protease “cleans up” dicarbonyl adducts on nucleotides as a protective mechanism. Interestingly, this enzyme, called DJ-1, also repairs proteins that have been similarly damaged by carbonyl modification. The study points to a possible new mechanism for repairing endogenous DNA damage.