Optimization of proteomics sample preparation for forensic analysis of skin samples

Area of Science:

• Proteomics
• Forensic Science
• Biochemistry

Background:

• Human skin cells contain proteins valuable for forensic identification.
• Current proteomics sample preparation needs optimization for forensic applications, especially for trace evidence like touch samples.

Purpose of the Study:

• To develop and optimize an efficient protein extraction and enzymatic digestion protocol for human skin samples.
• To enhance mass spectrometry-based proteomics for identifying genetically variable peptides (GVPs) for human identification.

Main Methods:

• Systematic optimization of digestion parameters (duration, temperature, surfactant) for human skin proteins.
• Utilized RapiGest surfactant and trypsin enzymatic digestion for 16 hours at 37°C.
• Applied mass spectrometry-based proteomics to mixed-donor skin samples, searching against a human proteome database with GVPs from known SNPs.

Main Results:

• Achieved maximized digestion completeness and repeatability.
• Identified a greater number of peptides and proteins with zero missed tryptic cleavages.
• Demonstrated the protocol's efficacy in identifying GVPs from mixed-donor skin samples.

Conclusions:

• The optimized protocol provides an efficient and reproducible method for skin protein analysis in forensic proteomics.
• This method supports the downstream analysis of GVPs, advancing protein-based human identification in forensic science.
• This work is a foundational step towards implementing GVP analysis in forensic laboratories.