Direct Peptide Reactivity Assay

Using our in house MALDI-TOF mass spectrometry instrument we can directly profile peptides and proteins in cell and tissue samples without any complex sample preparation. This technology uses collision induced fragmentation to obtain structural information from the mass-selected precursor ions of the analyte. This is a highly accurate method for the rapid identification of biomolecules in samples. This technique is also able to detect and identify post-translational modifications and can be used to characterize individual protein/peptides in complex mixtures.

Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry is a widely used, cost-effective analytical technique for the identification and quantification of proteins and direct peptides It is a non-invasive and high-resolution technique that allows for the analysis of samples with very low concentrations of analyte, making it ideal for screening and safety assessments in a variety of applications. It is especially well-suited for the identification of biologically important molecules such as hormones, proteins, peptides and antibodies in biological tissues and cells.

Direct Peptide Reactivity Assay (DPRA) is an in chemico test for skin sensitization that models the first key event in the Adverse Outcome Pathway (AOP) of skin sensitization – the covalent binding of electrophilic chemicals to nucleophilic amino acid residues in epidermal proteins. The DPRA test detects this reaction by analyzing the reactivity of a chemical sample with synthetic peptides containing the nucleophilic amino acids cysteine and lysine. These peptides are incubated with the test substance and the resulting depletion of lysine and cysteine in the sample is determined by HPLC with UV detection. Based on this depletion, chemicals are classified into four reactivity categories and discriminated between sensitizers and non-sensitizers.

This is a validated in vivo alternative to animal testing. Eurofins is one of the EURL ECVAM (European Centre for the Validation of Alternative Methods) Reference Laboratories performing DPRA testing in compliance with OECD guideline 442C.

Our DPRA analysis services are available for a variety of products including pharmaceuticals, cosmetics, personal care, chemicals, and natural and botanical ingredients. We can provide data output in accordance with OECD guidelines and Good Laboratory Practices to support your regulatory submissions.

This assay is a highly sensitive method that provides results within 24 hours. This is a very important benefit for time critical research applications where the need to be fast is of paramount importance. In addition, the DPRA system is very simple to use and requires no sample preparation, making it an extremely cost-effective testing option for small volume assays. The DPRA assay can be performed with samples in a variety of formulations, including topical solutions, liquids, powders and ointments. The DPRA is an excellent alternative to other skin sensitization tests such as the KeratinoSensTM and the h-CLAT tests.

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