Lysozyme is a protein substance present in biological secretions (saliva, tears, sperm secretions, nasal mucus, milk, etc.) and in eggs (albumen contains large quantities). This enzyme discovered in 1922 by Fleming, carries out a "interesting antimicrobial action, thanks to the ability to hydrolyze the peptidoglycans that make up the bacterial wall (the word lysozyme derives from the Greek: liso = what size e zimo = enzyme). Following the damage of this mechanically resistant structure, the bacterial cell draws water until it bursts.
It is no coincidence, therefore, that lysozyme is abundantly secreted in the body regions most exposed to contact with pathogens (oral cavity, conjunctiva, etc.). Its immune importance is evidenced by the fact that infants fed with lysozyme-free infant formula have a frequency of diarrheal episodes three times higher than infants fed with breast milk (in which, in addition to lysozyme, we also find antibodies).
The optimal pH for lysozyme to function is five; in the food sector it is used, also under the initials E1105, for the preservation of aged cheeses, including Grana Padano.
