Osmotic Shock

Reagents and Materials

• Induced cultures of protein-producing bacteria
• 20% w/v sucrose, 0.03 M Tris-HCl pH 8.0
• Ice-cold 5mM MgSO₄

Protocol

1. Culture and induce protein-producing bacteria
2. Spin down the cells for 10 min at 4,000 rpm
3. Re-suspend pellet in 10 ml of 20% w/v sucrose, 0.03 M Tris-HCl pH 8.0. Incubate for 10 minutes at room temperature
4. Pellet cells at 4°C for 10 minutes at 4,000 rpm
5. Re-suspend pellet in 200µL of ice-cold 5mM MgSO₄ and transfer into an eppendorf tube and let sit on ice bath for 30 minutes
6. Spin at >13,000 rpm for 10 minutes. Carefully remove the supernatant and transfer to new tube
7. Do SDS PAGE Gel analysis and store as required