Keratins are the most common protein contaminants derived primarily from human skin and hair, or sometimes from clothes like wool sweaters. These are tips for you to avoid keratin contamination of your sample:
1. Work in a clean lab with clean surfaces;
2. Use pipette tips and microcentrifuge tubes from closed boxes;
3. Rinse equipment in clean water before use (bottles, glass plates, electrophoresis equipment, staining trays);
4. Always wear gloves during your sample preparation and digestion. Never touch the gel with your fingers. Do not touch your hair or skin with gloved hands.