ANATOMY

Detailed explanation-1: -Lysozyme is a  14 kDa protein present in many mucosal secretions (tears, saliva, and mucus) and tissues of animals and plants, and plays an important role in the innate immunity, providing protection against bacteria, viruses, and fungi.

Detailed explanation-2: -Before discovering penicillin, Alexander Fleming discovered the enzyme lysozyme based on the ability of nasal secretions to prohibit bacterial growth [14]. Lysozyme is a naturally occurring enzyme found in bodily secretions such as tears, saliva, and milk.

Detailed explanation-3: -In fact, saliva is rich with effectors that exert direct antimicrobial activity, such as enzymatic breakdown of bacterial cell walls by lysozyme and sequestering iron by lactoferrin [4, 5].

Detailed explanation-4: -Lysozyme present in saliva and tears kills viruses by destroying their cell walls.

Detailed explanation-5: -Lysozyme degrades peptidoglycan in the bacterial cell wall leading to rapid killing of Gram-positive organisms; however, this mechanism cannot account for the protective effect of lysozyme against Gram-negative bacteria.