Proteomic methods, particularly bottom‐up proteomics, have continued to demonstrate their value in improving forensic applications related to protein mass spectrometry. Amino acid sequences not only reveal which human or non‐human proteins are present, they can also demonstrate variability between individuals. For DNA analysis, STR is still the primary tool to identify unique individuals.
In a recent study, a research team set out to determine if it was possible to obtain PCR‐STR results for mass spectrometry protein sequences and DNA analysis, when beginning with a single trypsin digestion sample (5). To test this, they utilized Millipore Microcon® MW100 filter units, replaced proteinase K with trypsin and sodium dodecyl sulfate (SDS) with ProteaseMAX.
Results indicated that trypsin digestion and Microcon® MW100 filtration method can be used to successfully and neatly separate DNA and protein components from fingerprints. In a parallel comparison with the standard proteinase K method, the Microcon® method revealed DNA yields similar to proteinase K extraction method and PCR‐STR results that were better.
The Microcon® method also produced peptides in the flow through that were particle‐free, in aqueous solution and mass spectrometry‐ready, indicating that this method is a suitable approach for forensic investigators to not only process touch evidence, but also test for tissue specific protein markers and protein polymorphisms.