(1) Ausubel, F.A., Brent, R., Kingston, R.E., Moore, D.D., Seidman, J.G., Smith, J.A. & Struhl, K. (eds.) 2001. Currrent Protocols in Molecular Biology. John Wiley & Sons, New York.
(2) Sambrook, J. & Russell, D.W. (2001) Molecular Cloning: A Laboratory Manual, 3rd Edition. pp. A1.8+4.51. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY.
Lysozyme (Muramidase) preferentially hydrolyses the β-1,4-glycosidic binding between N-Acetyl muraminic acid and N-Acetyl glucosamine, a component of the proteoglycan-cell wall of certain microorganisms. The enzyme is present in many organisms. In molecular biology, the enzyme from chicken white egg is used to lyse E. coli for the isolation of plasmid-DNA (ref. 1 miniprep: Suppl. 15; pp. 1.6.4-7). The working concentration is 200 μg/300 μl. To increase the plasmid yield (approx. 5 - 10 %) in the so-called ''''maxiprep'''', lysozyme may be added (ref. 1 maxiprep: Suppl. 41; pp. 1.7.2-4). Another application is the lysis of bacteria for the preparation of bacterial RNA (ref. 1 Suppl. 15; pp. 4.4.4-5). In this case the working concentration is 40 μg/ml (stock solution 50 mg/ml).
Form: The protein itself is Lysozyme chloride - the chloride is part of the protein structure. There is no free sodium chloride in the preparation. The maximum chloride content is 4 %.
Stability: The lyophilized powder of lysozyme is stable for many years at +4°C. In solution, the stability at pH values from 4 to 5 at +4°C is several weeks and at room temperature several days. The pH-optimum is at 9.2, the isoelectric point at 11.0. Lysozyme will be inhibited by surfactants like SDS or alcohols and fatty acids, imidazole and indol-derivatives. Stock solutions in 10 mM Tris · HCl (pH 8.0) are prepared with a concentration of 10, 25 or 50 mg/ml, usually just before use.