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Isolation of Highly Specific Protein Markers for the Identification of Biological Stains: Adapting Comparative Proteomics to Forensics

NCJ Number
Date Published
38 pages
This study tested the hypothesis that by rigorously comparing the "proteomic profiles" (proteins present in a substance) of six body fluids of particular value to the forensic community, a panel of high-specificity candidate protein biomarkers for individual body fluids could be identified.
The circumstance that warranted this project is the fact that although DNA profiling allows biological stains to be individualized, the unambiguous identification of the stain itself can present forensic serologists with a significant challenge; for example, there is no reliable test for vaginal secretions, and tests for blood cannot distinguish peripheral from menstrual blood. Such information can be probative to an investigation. This research confirmed the hypothesis. Through a combination of highly reproducible 2-Dimensional High-Performance Liquid Chromatography (2 D HPLC) proteome fractionation and implementation of customized clustering algorithms, high-resolution consensus proteomic profiles (2D pl/hydrophobicity maps) were produced for each of six different bodily fluids (saliva. semen, peripheral blood, menstrual blood, vaginal secretions, and urine). By conducting quantitative pair-wise comparisons among these datasets, it was possible to distinguish those proteins that were likely to be genuinely characteristic of a specific bodily fluid versus those that reflected inter-individual variability in protein expression. False negatives were minimized by normalizing the consensus datasets for subtle variations in pH, solvent gradients, and protein concentration. Based on these analyses, a comprehensive panel of candidate biomarkers was produced and characterized by mass spectrometry. A thorough validation of the specificity of these candidate biomarkers in a larger population group, as well as using forensic casework type samples, are the next steps in the development of a practitioners-ready high-specificity test for biological stain identification. 1 table, 11 figures, 28 references, and a listing of talks and posters on the research findings

Date Published: January 1, 2011