Question

What is lysozyme? What is its function?

Answer 1

The enzyme Lysozyme functions by attacking, hydrolyzing, and breaking the glycosidic bonds present in peptidoglycans. The enzyme also breaks the glycosidic bonds in chitin, though not as successfully as the true chitinases.

Complete answer:
Lysozyme is an enzyme which is found in the secretions of the lacrimal glands of animals such as tears and in other secretions like nasal mucus, gastric secretions, and egg white. Lysozyme was discovered by Sir Alexander Fleming in 1921. It catalyses the breakdown of several carbohydrates which are found in the cell walls of some bacteria such as cocci.
The active site of lysozymes binds to the peptidoglycan compound in the prominent split between the two domains. It attacks the peptidoglycans which are found in the cell walls of bacteria, particularly Gram-positive bacteria which is its natural substrate. The enzyme acts between the N-acetylmuramic acid (NAM) and the fourth carbon of the N-acetylglucosamine (NAG).
Lysozyme is present in abundance in secretions such as tears, saliva, human milk, and mucus. The enzyme is also present in the cytoplasmic granules of the macrophages and in the polymorphonuclear neutrophils (PMNs). Huge quantities of lysozyme are found in egg white. In the case of humans, the C-type lysozyme is encoded by LYZ gene.

Lysozyme enzyme is a dense protein which contains 129 amino acids which fold into a compressed globular structure. Lysozyme contains two conformations: 1) An open active state 2) A closed inactive state.

Note: Lysozyme shows more effect against the gram-positive bacteria than the gram-negative bacteria as the gram-positive bacteria has more amount of peptidoglycans in the cell wall. Lysozyme is an important part of the immune system.