Lactoperoxidase (LPO)

Lactoperoxidase is a heme-containing peroxidase enzyme present primarily in mammalian milk, saliva, tears, and other mucosal secretions[3][4][5]. It catalyzes the hydrogen peroxide-dependent oxidation of several substrates, including thiocyanate, iodide, and bromide, resulting in the formation of strongly antimicrobial oxidized products (such as hypothiocyanite and hypoiodite)[1][3][9]. Its main physiological role is to provide a broad-spectrum, non-specific antimicrobial defense at mucosal surfaces and in milk, forming part of the innate immune system that protects against a wide array of pathogens, including bacteria and viruses[3][4]. Structurally, lactoperoxidase is a single-chain glycoprotein, typically about 78–80 kDa in size, and contains a covalently linked heme (protoporphyrin IX) group at its catalytic center[2][5][7]. The enzyme's activity is highly dependent on the presence of both hydrogen peroxide and appropriate electron donors such as thiocyanate. Variants exist between species, but the enzyme’s function and structure are highly conserved. Practically, the lactoperoxidase system is exploited for its preservative and antimicrobial properties in food safety, personal care products, and sometimes as an adjunct in oral and dairy health applications. Safety issues are minor in physiological contexts, but excessive or unregulated activity could shift the system toward oxidative stress, underlying its potential implication in certain pathologies, such as breast cancer via oxidative modification of hormones[3]. If you need more specific drug information, consider that while no classic drugs target LPO itself, its substrates and cofactors (like hydrogen peroxide and thiocyanate) are used in functional systems to harness its antimicrobial effects (the "lactoperoxidase system") for food safety and oral care purposes[9].

Other names

lactoperoxidase enzymeLPOEC 1.11.1.7

Enzymatic oxidation: lactoperoxidase uses hydrogen peroxide to catalyze oxidation of thiocyanate and halides (iodide, bromide) to produce potent antimicrobial compounds (e.g., hypothiocyanite, hypoiodite). The antimicrobial effect results from the oxidative destruction of bacterial cell structures and suppression of microbial growth.