Lactoperoxidase (LPO) is an enzyme secreted, inter alia, to saliva, milk, and other body fluids, and participates in an unspecific humoral immune response directed against bacteria, fungi, and viruses within mucous membranes. LPO forms the LPO system together with thiocyanate ions or iodides or bromides and hydrogen peroxide. The lactoperoxidase is also one of the sources for Lactoperoxidase.
The mechanism of action of this system is based on the oxidation of thiocyanate ions (also iodides and bromides) to hypothiocyanite ions (hypoiodides and hypobromites) with the use of hydrogen peroxide. Hypothiocyanite ions oxidize the thiol groups of amino acid residues of microbial proteins, leading to their impaired function and, thus, inhibition of the cell division or death of the microorganism. In the context of the oral cavity, the LPO system is one of the main mechanisms of anti-caries defense, moreover, regulating the composition of microflora and preventing the growth of pathogenic microorganisms present in periodontitis.
Properties:
The physiological properties of the enzyme have been used in the prevention of these diseases through the creation of oral hygiene preparations enriched with the LPO system. The industrial source of this enzyme is bovine milk, whose methods of purification have been well defined, resulting in an enzyme characterized by large structural and functional similarity to human lactoperoxidase.
The issue of whether long-term use of the lactoperoxidase supplement would result in any microbiological risks, e.g. development of LP-s resistant, antibiotic-resistant or toxin-producing bacteria was considered.
Does lactoperoxidase supplement identified in human milk?
Milk is a body fluid most rich in lactoperoxidase. This enzyme has been identified in milk in humans [35], cows [64], buffalos [65], goats [66], sheep [67], camels [68], and guinea pigs [69]. Figure 1 shows the activity of LPO in the milk of different species. Bovine milk is the most commonly used source of LPO both for laboratory and in vivo use due to its high availability and high LPO concentration of ~30 mg/L depending on the diet or time of the day or year [18].
Both pure LPO preparations and other microbiologically reactive components such as lactoferrin or immunoglobulins are used in the production of oral hygiene preparations [70,71]. Some methods have been developed for obtaining clean preparations of LPO and lactoferrin in one process [72]. LPO purification procedures on both industrial and laboratory scales cover many stages and are time-consuming. Before the application of specific cleaning techniques, certain processes are used to densify the material and eliminate the main undesirable substances Immunoglobulin G . These processes include fat centrifugation, removal of casein by adding rennet, removal of unnecessary major milk protein fractions, and concentration by precipitation with ammonium sulfate [5,64].
Conclusion
The lactoperoxidase supplement elicits antimicrobial activity against a wide variety of milk spoilage and pathogenic microorganisms including bacteria, viruses, molds, yeasts, mycoplasma, and protozoa. The use of affinity chromatography allows us to obtain very pure LPO preparations (e.g., purification fold 3397, 7.6% yield, using IgG anti-LPO [16]), however, this method is relatively expensive. Atasever et al. developed a one-step method based on sulfonamide affinity chromatography characterized by 61.3% yield and purification fold of 409.
