A possible new role for the anti-ageing peptide carnosine

The naturally occurring dipeptide carnosine (beta-alanyl-L-histidine) is fo und in surprisingly large amounts in long-lived tissues and can delay agein g in cultured human fibroblasts. Carnosine has been regarded largely as an anti-oxidant and free radical scavenger. More recently, an anti-glycating p otential has been discovered whereby carnosine can react with low-molecular -weight compounds that bear carbonyl groups (aldehydes and ketones). Carbon yl groups, arising mostly from the attack of reactive oxygen species and lo w-molecular-weight aldehydes and ketones, accumulate on proteins during age ing. Here we propose, with supporting evidence, that carnosine can react wi th protein carbonyl groups to produce protein-carbonyl-carnosine adducts (' carnosinylated' proteins). The various possible cellular fates of the carno sinylated proteins are discussed. These proposals may help explain anti-age ing actions of carnosine and its presence in non-mitotic cells of long-live d mammals.