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Lactoperoxidase is a member of benzamides.
Lactoperoxidase is a bacterial cell wall protein, which has high affinity for immunoglobulin G (IgG).
Lactoperoxidase is isolated from group G streptococcal strains.
CAS: 9003-99-0
MF: NULL
MW: 0
EINECS: 232-668-6
Synonyms
Peroxidase froM horseradish(EIA Grade,Purified);84 kDa myeloperoxidase;89 kDa myeloperoxidase;ANTI-MYELOPEROXIDASE(N-TERMINAL) antibody produced in rabbit;Myeloperoxidase light chain;Apoperoxidase;Peroxidase isoenzymes Type XI: Apoenzyme from horseradish;ANTI-MYELOPEROXIDASE (CENTER) antibody produced in rabbit
Lactoperoxidase from Streptococcus sp. is used to maintain the H2O2 homeostasis in cells.
Lactoperoxidase aids the regulation of ABC Mn2+-permease complex (psaBCA) genes.
Lactoperoxidase is a peroxidase enzyme secreted from mammary, salivary, tears and other mucosal glands including the lungs, bronchii and nose that function as a natural, first line of defense against bacteria and viral agents.
Lactoperoxidase is a member of the heme peroxidase family of enzymes.
In humans, Lactoperoxidase is encoded by the LPO gene.
Lactoperoxidase catalyzes the oxidation of several inorganic and many organic substrates by hydrogen peroxide.
Lactoperoxidase rapidly oxidizes iodide and slowly oxidizes bromide and is designated a haloperoxidase.
Another important substrate is the pseudo-halide thiocyanate.
The oxidized products display potent, non-specific bactericidal and antiviral activities, including destruction of the influenza virus.
Lactoperoxidase together with its inorganic ion substrates, hydrogen peroxide, DUOX1 and DUOX2 and products are termed the lactoperoxidase system.
Hence LPO is considered a very important defense against invasive bacteria and viral agents such as influenza and the SARS-CoV-2 virus when sufficient iodine is provided.
The LPO system plays an important role in the innate immune system by destroying bacteria in milk and mucosal (linings of mostly endodermal origin, covered in epithelium involved in absorption and secretion) secretions.
Hence augmentation of the lactoperoxidase system may have therapeutic applications and applications for controlling bacteria in food and consumer health care products.
This system does not vigorously attack DNA and is not mutagenic.
However, under certain conditions, the LPO system may contribute to oxidative stress though recent evidence indicates LPO to be protective.
Lactoperoxidase may contribute to the initiation of breast cancer, through its ability to oxidize estrogenic hormones producing free radical intermediates.
Lactoperoxidase is an enzyme derived from milk.
Lactoperoxidase is also found in the human body’s saliva and mucosal systems and serves as a defense against surface microbial infection.
In the dairy industry, Lactoperoxidase is used to deter the proliferation of harmful bacteria in milk and milk products.
In skin care, lactoperoxidase’s natural antimicrobial action helps restore skin’s surface flora (its microbiome), leading to a healthier, more hydrated look and feel, and an improvement in pore function.
Lactoperoxidase is considered safe as used in cosmetics.
Milk is a highly nutritious food and an excellent source of energy, protein, vitamins and minerals.
However, Lactoperoxidase is also an ideal medium for microbial growth and fresh raw milk easily deteriorates to become unsuitable for processing and human consumption.
There are numerous processes for prolonging the shelf-life of milk and dairy products and an increasing array of technologies that can be applied to improve its safety and quality, including refrigeration, pasteurization, microfiltration and high pressure processing.
Lactoperoxidase (LPO) present in saliva are an important element of the nonspecific immune response involved in maintaining oral health.
The main role of this enzyme is to oxidize salivary thiocyanate ions (SCN−) in the presence of hydrogen peroxide (H2O2) to products that exhibit antimicrobial activity.
Lactoperoxidase Chemical Properties
Density: 1.37[at 20℃]
Vapor pressure: 0.004Pa at 25℃
Storage temp.: -20°C
Solubility H2O: soluble
Form: powder
Color: red-brown
PH: 6.5-7.5 (20°C, 10g/L in H2O)
Biological source: human leucocytes
Water Solubility: Soluble in water and phosphate buffer.
Specific Activity: 200-300units/mg solid (using pyrogallol)
LogP: -1.3 at 20℃
EPA Substance Registry System: Lactoperoxidase (9003-99-0)
Uses
Lactoperoxidase is a glycoprotein with anti-microbial activity, it is used as a stabilizing ingredient to help improve formulation stability and product shelf-life.
Lactoperoxidase is naturally occurring in milk.
Peroxidases (EC 1.11.1.x) are a diverse group of oxidoreductases using peroxide as an electron acceptor.
Their substrate spectrum ranges from hydrogen peroxide decomposed by catalase (hydrogen-peroxide:hydrogen-peroxide oxidoreductase, EC 1.11.1.6), phenolic compounds degraded by Mn-dependent and lignin peroxidases (Mn(II):hydrogen-peroxide oxidoreductase, EC 1.11.1.13 and 1,2-bis (3,4-dimethoxyphenyl)propane-1,3-diol:hydrogen-peroxide oxidoreductase, EC 1.11.1.14), and recalcitrant dyes by DyP-type peroxidases (reactive-blue- 5:hydrogen-peroxide oxidoreductase, EC 1.11.1.19).
Direct supplementation of peroxidases to food was applied for the degradation of carotenoids used for coloring of cheese.
The whey resulting from colored cheese production has an orange-yellowish tint, which interferes with further usage of the whey.
Recently, a fungal peroxidase of the DyP-type was commercialized for bleaching of this kind of whey fluid under the name MaxiBright (DSM).
To generate the hydrogen peroxide required by the peroxidase as a cofactor in situ, a glucose oxidase and a b-galactosidase were employed as auxiliary enzymes.
Lactoperoxidase, horseradish is used in the oxidation of luminol to 3-aminophthalate.
Lactoperoxidase is often used in conjugates to determine the presence of a molecular target, especially in the detection of specific protein in a western blot after conjugation with antibody.
Further, Lactoperoxidase is highly reactive toward human tumor cells.
Lactoperoxidase is an effective antimicrobial and antiviral agent.
Consequently, applications of lactoperoxidase are being found in preserving food, cosmetics, and ophthalmic solutions.
Furthermore, lactoperoxidase have found application in dental and wound treatment.
Finally lactoperoxidase may find application as anti-tumor and anti viral agents.
Lactoperoxidase has been used with radioactive iodine to selectively label membrane surfaces.
Dairy products
Lactoperoxidase is an effective antimicrobial agent and is used as an antibacterial agent in reducing bacterial microflora in milk and milk products.
Activation of the lactoperoxidase system by addition of hydrogen peroxide and thiocyanate extends the shelf life of refrigerated raw milk.
Lactoperoxidase is fairly heat resistant and is used as an indicator of overpasteurization of milk.
Oral care
A lactoperoxidase system is claimed to be appropriate for the treatment of gingivitis and paradentosis.
Lactoperoxidase has been used in toothpaste or a mouthrinse to reduce oral bacteria and consequently the acid produced by those bacteria.
Cosmetics
A combination of lactoperoxidase, glucose, glucose oxidase (GOD), iodide and thiocyanate is claimed to be effective in the preservations of cosmetics.
Cancer
Antibody conjugates of glucose oxidase and to lactoperoxidase have been found to effective in killing tumor cells in vitro.
In addition, macrophages exposed to lactoperoxidase are stimulated to kill cancer cells.
Knockout mice deficient in lactoperoxidase suffer ill-health and develop tumors.
Biological Functions
Peroxidases are widely distributed in plants, animals, and microorganisms, and they protect cells against the effects of oxidative stress and cell damage due to H2O2.
Peroxidases (EC number 1.11.1.x) represent a large family of oxidoreductases known to catalyze the oxidation of various inorganic and organic substrates using H2O2.
They have a common catalytic mechanism for the degradation of H2O2, a two-electron oxidation-reduction with three distinct steps.
They are involved in biological processes such as the breakdown of toxins, heavy metal detoxification and hormone regulation.
Additionally, they are used as catalysts in various industries, in clinical biochemistry, enzyme immunoassays, the removal of peroxides from industrial wastes and the synthesis of various aromatic chemicals.
Function
Lactoperoxidase catalyzes the hydrogen peroxide (H2O2) oxidation of several acceptor molecules:
reduced acceptor + H2O2 → oxidized acceptor + H2O
Specific examples include:
thiocyanate (SCN−) → hypothiocyanite (OSCN−)
iodide (I−) → hypoiodite (IO−)
bromide (Br−) → hypobromite (BrO−)
Depending on conditions the turnovers with SCN− or I− are roughly similar.
The turnover with Br− is about 10−4 smaller than the other two anions.
In mammals the source of hydrogen peroxide is one of the duox1 or duox2 enzymes which reduce dioxygen to H2O2 by oxidizing NADPH.
In the laboratory the source of the hydrogen peroxide (H2O2) usually is the reaction of glucose with oxygen in the presence of the enzyme glucose oxidase (EC 1.1.3.4) that also takes place in saliva.
Glucose, in turn, can be formed from starch in the presence of the saliva enzyme amyloglucosidase (EC 3.2.1.3).
These relatively short lived oxidized intermediates have potent bactericidal effects, hence lactoperoxidase is part of the antimicrobial defense system in tissues that express lactoperoxidase.
The lactoperoxidase system is effective in killing a range of aerobic and certain anaerobic microorganisms.
Research (1984): "The effect of lactoperoxidase-thiocyanate-hydrogen peroxide mixtures on bacteria is dependent on experimental conditions.
If the bacteria are cultured after the exposure to lactoperoxidase-thiocyanate-hydrogen peroxide on nutrient agar under aerobic conditions, they may not grow, whereas they grow readily on blood agar under anaerobic conditions."
In its antimicrobial capacity, lactoperoxidase appears to acts synergistically with lactoferrin and lysozyme.
Structure
The structure of lactoperoxidase consists mainly of alpha-helices plus two short antiparallel beta-strands.
Lactoperoxidase belongs to the heme peroxidase family of mammalian enzymes that also includes myeloperoxidase (MPO), eosinophil peroxidase (EPO), thyroid peroxidase (TPO), and prostaglandin H synthase (PGHS).
A heme cofactor is covalently bound near the center of the protein.
