The DPRA supports the discrimination between sensitising and non-sensitising chemicals. It measures in chemico the binding of test chemicals to model synthetic peptides containing either lysine or cysteine.
Within the skin sensitization Adverse Outcome Pathway the covalent binding of electrophilic chemicals with nucleophilic sites of amino acids in skin proteins is postulated to be the molecular initiating event (MIE) (i.e. key event 1 – protein binding reactions) leading to skin sensitisation.
In skin proteins many amino acids contain electron-rich groups capable of reacting with sensitisers. Lysine and cysteine are those most often quoted but others such as arginine, histidine, methionine and tyrosine can react with electrophilic chemicals.
