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Natural Preservatives
Published in Philip A. Geis, Cosmetic Microbiology, 2020
Lactoperoxidase belongs to the peroxidase family of enzymes and has been established as a key component of a broader system in nature which yields natural antibacterial components as part of the body’s defense. The lactoperoxidase effect was first observed in milk. In situ, the mechanism involves the reaction of lactoperoxidase with hydrogen peroxide (from the presence of existing bacteria) and electron donors like the thiocyanate ion to produce a cascade of antimicrobial metabolites (e.g., hypothiocyanate). Commercially available systems typically use a second component system. The first component consists of the enzymes lactoperoxidase and glucose oxidase. The second component contains the substrates glucose, thiocyanate, and iodide. In combination with oxygen, a reaction is catalyzed, yielding the antimicrobial metabolites hypoiodite and hypothiocyanite (Figure 3.6).
Dental Caries: Resistance Factors — Enamel Chemistry and Saliva
Published in Lars Granath, William D. McHugh, Systematized Prevention of Oral Disease: Theory and Practice, 2019
Stephen H. Y. Wei, James J. Crall, James S. Wefel
Three nonimmunological glycoproteins which have been identified as potential salivary defense factors are lysozyme, lactoperoxidase, and lactoferrin.8 Lysozyme is present in all body fluids and can cause cell wall disruption which leads to cell death. However, few species of bacteria have been shown to be susceptible to lysis by this substance under normal oral conditions. Lysozyme can still be bactericidal and cause aggregation without lysis, but its role in preventing caries is as yet equivocal. The lactoperoxidase system has been shown to inhibit growth and acid production by a number of organisms including streptococci and lactobacilli and reduce plaque accumulation.41 Lactoferrin is an iron-binding protein capable of exerting a bactericidal effect on several organisms including S. mutans.8 It has been postulated to enhance the antibacterial effect of lysozyme. These three antibacterial substances may act in concert with immunological factors to reduce the cariogenic challenge.
Methods of Protein Iodination
Published in Erwin Regoeczi, Iodine-Labeled Plasma Proteins, 2019
Self-iodination is defined as the process whereby a radioactive substitution takes place in an enzyme molecule (or in a protein contaminating it) instead of the protein to be labeled. Lactoperoxidase (or its contaminants) can certainly become labeled (Figure 25), but the extent to which this happens has been sparsely documented. Under iodinating conditions, but in the absence of a protein to be iodinated, 568 and 10%69 of the radioactivity have been found to have become associated with the enzyme, respectively. It seems a reasonable expectation that with a proper protein substrate present, the extent of self-iodination should be less, particularly if the substrate/catalyst mass ratio is high.
Inhibition effects of selected thiophene-2-sulfonamides on lactoperoxidase
Published in Drug and Chemical Toxicology, 2021
Lactoperoxidase (LPO, E.C. 1.11.1.7) is an important milk-protein with oxidoreductase activity. LPO is mostly found in the breast tissue, saliva, and lachrymal glands of mammalians including human, bovine, buffalo, goat, sheep, lama, cow, camel, and mouse (Koksal et al.2017a). The main functions of the enzyme are to catalyze the oxidation of molecules in the presence of hydrogen peroxide and aid in the production of molecules with a wide range of antimicrobial activity. In the presence of hydrogen peroxide, the system catalyzes the transformation of thiocyanate into hypothiocyanate, which has antibacterial properties (Reiter and HaÈrnulv 1984, Reiter and Perraudin 1991, Kussendrager and Van Hooijdonk 2000). LPO has several potential areas of application which are expected to increase, various researchers are currently conducting purification studies to decrease the costs associated with the purification of LPO (Morrison and Hultquist 1963, Seifu et al.2005, Ozdemir and Uguz, 2005, Boots and Floris, 2006), and extensive studies are being conducted to identify the novel inhibitors of LPO (Koksal et al.2016a, 2016b, 2017a, 2017b).
Lactoperoxidase, an antimicrobial enzyme, is inhibited by some indazoles
Published in Drug and Chemical Toxicology, 2020
Lactoperoxidase (LPO, E.C. 1.11.1.7) is an important milk-protein with oxidoreductase activity. Peroxidase isolated from the milk was called LPO (Reiter and Harnulv 1984), and it was the first enzyme discovered in milk (Arnold 1881). The main functions of the enzyme are to catalyze the oxidation of molecules in the presence of hydrogen peroxide and to aid in the production of molecules with a wide range of antimicrobial activity. Pseudohalogens, thiocyanates or halogens function as the secondary substrates for the enzyme and demonstrate a similar antimicrobial activity (Reiter and Perraudin 1991). LPO is mostly found in the breast tissue, saliva and lachrymal glands of mammalians, including human, bovine, buffalo, goat, sheep, lama, cow, camel and mouse (Koksal et al.2017a).