Lysozyme from chicken egg white

Lysozyme is abundantly found in animal and plant kingdoms. It is a natural food preservative and also found to be present in specific bacterial cell walls. Lysozyme is usually present in tears, milk, urine and saliva.

Lysozyme from chicken egg white has been used:

• in dielectric spectroscopy studies of dynamics of protein
• as a control to measure the human lysozyme activity
• as a supplement in soaking solution to treat lenses

Enzyme breaks down the cell walls of bacteria; used to prepare spheroplasts.

Lysozyme hydrolyzes β(1→4) linkages between N-acetylmuramic acid and N-acetyl-D-glucosamine residues in peptidoglycan and between N-acetyl-D-glucosamine residues in chitodextrin. Gram-positive cells are quite susceptible to this hydrolysis as their cell walls have a high proportion of peptidoglycan. Gram-negative bacteria are less susceptible due to the presence of an outer membrane and a lower proportion of peptidoglycan. However, these cells may be hydrolyzed in the presence of EDTA that chelates metal ions in the outer bacterial membrane.

The enzyme is active over a broad pH range (6.0 to 9.0). At pH 6.2, maximal activity is observed over a wider range of ionic strengths (0.02 to 0.100 M) than at pH 9.2 (0.01 to 0.06 M).

Lysozymes participate in the defense mechanism. It has the ability to stimulate catalysis by bringing steric stress in the substrates.

One unit will produce a ΔA₄₅₀ of 0.001 per min at pH 6.24 at 25°C, using a suspension of Micrococcus lysodeikticus as substrate, in a 2.6 mL reaction mixture (1 cm light path).

3× crystallized