Lysine peptide

Lysine peptide (Ac RFAAKAA COOH) is used in combination with cysteine peptide (Ac RFAACAA COOH) in the Direct Peptide Reactivity Assay (DPRA) test. Direct Peptide Reactivity Assay is used in cosmetic applications for the characterization of the skin sensitizing potential of a substance, framed by OECD Guideline no 442. The molecular initiating event (MIE) in skin sensitization is a binding between epidermal proteins and the sensitizing chemical substance. MIE is part of the adverse outcome pathway (AOP) of skin sensitization. It is thanks to the properties of Lysine peptide and Cysteine peptide that the chemical binding will be able to take place, so these synthetic heptapeptides will mimic the reaction of a skin exposed to a substance. Binding between nucleophilic proteins and electrophile substance will be measured by High Performance Liquid Chromatography (HPLC) . Therefore, the decrease in Lysine peptide and Cysteine peptide levels will be a sign of sensitizing event. Depending on the rate of depletion, the sensitizing character of a molecule will be determined (see table at the bottom of the page) . In chemico DPRA test also has wider applications such as hazard classification in cosmetics, but also for pharmaceuticals and biocides. It is a good alternative to animal experimentation.