Division 5.2.1

Prepare a lysozyme solution containing 10 mg lysozyme (Sigma L–6876) in 10 ml buffer (100 mM Tris-HCl, 50 mM EDTA, pH8.0). This solution can be stored but it should only be freeze-thawed once. Cover each sample well with approximately 50 µl of lysozyme solution and incubate for 10 minutes at room temperature. Then dip the slides in demineralised water, once only and dry with filter paper.

Alternatively, instead of lysozyme add 50 µl of 40 to 400µg ml^–1 proteinase K in buffer (20 mM Tris-HCl, 2 mM CaCl₂, pH 7,4) to each well and incubate at 37 °C for 30 minutes.