Question

Explain why would the lysozyme stock solution show virtually the same activity as the boiled lysozyme stock solution?

Answer 1

Lysozyme is an antimicrobial enzyme produced by animals that forms part of the innate immune system. Lysozyme is a glycoside hydrolase that catalyzes the hydrolysis of 1,4-beta-linkages between N-acetylmuramic acid and N-acetyl-D-glucosamine residues in peptidoglycan, which is the major component of gram-positive bacterial cell wall.

Lysozyme is abundant in secretions including tears, saliva, human milk, and mucus. It is also present in cytoplasmic granules of the macrophages and the polymorphonuclear neutrophils (PMNs). Large amounts of lysozyme can be found in egg white.

Hen egg white lysozyme is thermally stable, with a melting point reaching up to 72°C at pH 5.0.Hence even after boiling the stock lysozyme will show the same activity virtually .Most of the lysozyme enzyme used are prepared from egg white hence they are stable thermally . Howeverw, lysozyme in human milk loses activity very quickly at that temperature.Hen egg white lysozyme maintains its activity in a large range of pH (6-9). Its isoelectric point is 11.35. The isoelectric point of human milk lysozyme is 10.5-11.