Lactoperoxidase Peroxidase

HORSERADISH PEROXIDASE LACTOPEROXIDASE LIGNAN PEROXIDASE LYSYL OXIDASE MANGANESE PEROXIDASE MYELOPEROXIDASE OVOPEROXIDASE PEROXIDASE PYRUVATE OXIDASE XANTHINE OXIDASE Hydrogen selenide,... 

The occurrence of a peroxidase, lactoperoxidase (LPO), in milk was recognized as early as 1881. It is one of the most heat-stable enzymes in milk its destruction was used as an index of flash pasteurization (now very rarely used) and is now used as an index of super-HTST pasteurization. 

Peroxidases from animal sources which have been studied are thyroid peroxidase, lactoperoxidase, myeloperoxidase and glutathione peroxidase. Lactoperoxidase and... 

Thus the chloride/chlorine couple has a redox potential of 1.36 V and can be oxidised by myeloperoxidase and eosinophil peroxidase lactoperoxidase can oxidise bromide (E° = 1.07 V) whereas thyroid peroxidase can only oxidise thiocyanate (E° = 0.77 V) and iodide (E° = 0.54V). All these reactions are two-electron oxidations and there is no evidence for a stable one-electron intermediate, i.e., compound II does not build up as a stable intermediate, and in fact can be inhibitory if it does form in significant concentrations [21]. 

Hemoproteins are a broad class of redox-proteins that act as cofactors, e.g. cytochrome c, or as biocatalysts, e.g. peroxidases. Direct ET between peroxidases such as horseradish peroxidase, lactoperoxidase," or chloropcroxidasc"" and electrode surfaces, mainly carbonaceous materials, were extensively studied. The mechanistic aspects related with the immobilized peroxidases on electrode surfaces and their utilization in developing biosensor devices were reviewed in detail. The direct electrical contact of peroxidases with electrodes was attributed to the location of the heme site at the exterior of the protein that yields close contact with the electrode surface even though the biocatalyst is randomly deposited on the electrode. For example, it was reported " that non-oriented randomly deposited horseradish peroxidase on a graphite electrode resulted in 40-50% of the adsorbed biocatalyst in an electrically contacted configuration. For other hemoproteins such as cytochrome c it was found that the surface modification of the electrodes with promoter units such as pyridine units induced the binding of the hemoproteins in an orientation that facilitated direct electron transfer. By this method, the promoter sites induce a binding-ET process-desorption mechanism at the modified electrode. Alternatively, the site-specific covalent attachment of hemoproteins such as cytochrome c resulted in the orientation of the protein on the electrode surfaces and direct ET communication. ... 

Some of these enzymes such as chloroperoxidase from Caldariomyces Jumago, horseradish peroxidase, lactoperoxidase from bovine milk, and myeloperoxidase from human white blood cells are commercially available. 

Keywords H5rpothiocyanite Thiocyanate Pseudohalide Peroxidase Lactoperoxidase Myeloperoxidase Antimicrobial Kinetics Mechanism. 

Figure 2. Redox cycles occurring in the 3-dimensional redox epoxy hydrogel. POD represents any of the following enzymes native horseradish peroxidase, NaI04 treated horseradish peroxidase, lactoperoxidase, or Arthromyces ramosus peroxidase.

Nitric oxide and nitrite react with other peroxidase enzymes such as horseradish peroxidase (HRP) (138a,139), lactoperoxidase (138a) and eosinophil peroxidase (140) similarly. The rate constants for reaction of NO with compounds I and II in HRP were found to be 7.0 x 105M 1s 1 and 1.3 x 106M 1s 1, respectively (139). Catalytic consumption of NO as measured by an NO sensitive electrode in the presence of HRP compounds I and II is shown in Fig. 5 where accelerated consumption of NO is achieved even in deoxygenated solutions (140). 

Peroxidases have also been utilized for preparative-scale oxidations of aromatic hydrocarbons. Procedures have been optimized for hydroxylation of l-tyrosine, D-(-)-p-hydroxyphenylglycine, and L-phenylalanine by oxygen, di-hydroxyfumaric acid, and horseradish peroxidase (89). Lactoperoxidase from bovine milk and yeast cytochrome c peroxidase will also catalyze such hydroxylation reactions (89). 

Glucose oxidase, in combination with peroxidase or lactoperoxidase Polynucleotide phosphorylase... 

Peroxidases. Another group of enzymes, which is involved in the oxidation of xenobiotics, is the peroxidase. There are a number of these enzymes in mammalian tissues prostaglandin synthase found in many tissues, but especially seminal vesicles and also the kidney, the lung, the intestine spleen, and blood vessels lactoperoxidase found in mammary glands myeloperoxidase found in neutrophils, macrophages, liver Kupffer cells, and bone marrow cells. 

The human body contains lactoperoxidase, a product of exocrine secretion into milk, saliva, tears, etc., and peroxidases with specialized functions in saliva, the thyroid, eosinophils,219 and neutrophils.220 The functions are largely protective but the enzymes also participate in biosynthesis. Mammalian peroxidases have heme covalently linked to the proteins, as indicated in Fig. 16-12 220 222a... 

As discussed in the earlier survey (1), a biogenic source of polychlorinated dibenzo-p-dioxins and dibenzofurans is peroxidase-catalyzed transformation of chlorophenols as first reported by Oberg and Rappe (2041-2044). More recent studies confirm these observations (2045-2048). In addition to lactoperoxidase and horseradish peroxidase, human leukocyte myeloperoxidase catalyzes in vitro formation of dioxins and dibenzofurans from chlorophenols (2046, 2047). Formation rates are in the pmol/mol range (Scheme 3.6) demonstrating that a human biosynthesis of dioxins and furans is not only possible but also likely. These observations are reinforced by the reported in vivo (rats) conversion of the pre-dioxin nona-chloro-2-phenoxyphenol to octachlorodibenzo-p-dioxin (OCDD) (2049), and the production of hepta- and octachlorodibenzo-p-dioxin in the feces of cows fed pentachlorophenol-treated wood (Scheme 3.7) (2050, 2051). 

After the first discovery of the asymmetric sulfoxidation by Kobayashi et al. [226], it could be shown that a large number of aryl alkyl sulfides are oxygenated with enantiomeric excesses higher than 98% [227-229]. Other peroxidases also catalyze this reaction. Interestingly, the plant peroxidase HRP [230] yields the (S)-sulfoxide, whereas mammalian myeloperoxidase [223] and lactoperoxidase [231] catalyze the formation of the R-enantiomers. The stereospecific sulfoxidation of aryl alkyl sulfides by purified toluene dioxygenase (TDO) from P. putida was also studied in this context [232] and showed that sulfoxidation yielded the (S)-sulfoxides in 60-70% yield, whereas CPO under the same conditions yielded 98% (R)-sulfoxides (Scheme 2.15). CPO is thus again an exception from the rule in that it produces R-enantiomeric sulfoxides, besides its bacterial origin [227]. The reason for this behavior lies in the... 

The direct interactions between metals and ONOO- can catalyze modifications. For example, the metals in Cu,Zn SOD and FeEDTA (EDTA = ethyl-enediaminetetraacetic acid) enhance nitration reactions (229). Heme-containing enzymes such as myeloperoxidase (6 x 106A/-1 s-1) and lactoperoxidase (3.3 x 105M-1s-1) also react with ONOO- (230) such that compound II [FeIV(P+)0] is formed. In contrast, horseradish peroxidase (3.2 x 106M-1 s-1) is converted to compound I (FevO) by ONOO-. Floris et al. (230) proposed an interesting mechanism by which compound I is initially produced and then rapidly oxidizes NO-f to N02. In the presence of NO, a number of nitrosation reactions would subsequently be facilitated by subsequent formation of N2O3 (Eq. 32). 

Fig. 2.7 Detail of the reconstructed phylogenetic tree showing the subfamily of vertebrate peroxidases including the mammalian enzymes myeloperoxidase (MPO), eosinophil peroxidase (EPO), lactoperoxidase (LPO), and thyroid peroxidase (TPO). Reproduced from [10] with the permission of John Wiley and Sons (License Nr. 2326000554179)...

Battistuzzi G, Bellei M, Vlasits J et al (2010) Redox thermodynamics of lactoperoxidase and eosinophil peroxidase. Arch Biochem Biophys 494 72-77... 

Furtmuller PG, Amhold J, Jantschko W et al (2005) Standard reduction potentials of all couples of the peroxidase cycle of lactoperoxidase. J Inorg Biochem 99 1220-1229... 

Kimura S, Yamazaki I (1979) Comparisons between hog intestinal peroxidase and bovine lactoperoxidase-compound I formation and inhibition by benzhydroxamic acid. Arch Bio-chem Biophys 198 580-588... 

Ferrari RP, Laurenti E, Casella L, Poli S (1993) Oxidation of catechols and catecholemines by horseradish peroxidase and lactoperoxidase ESR spin stabilization approach combined with optical methods. Spectrochim Acta 49A 1261-1267... 

Doerge DR (1986) Oxygenation of organosulfur compounds by peroxidases evidence of an electron transfer mechanism for lactoperoxidase. Arch Biochem Biophys 244 678-685... 

Doerge DR, Cooray NM, Brewster ME (1991) Peroxidase-catalyzed S-oxygenation mechanism of oxygen transfer for lactoperoxidase. Biochemistry 30 8960-8964... 

Casella L, Gullotti M, Poli S et al (1991) Spectroscopic and binding studies on the stereoselective interaction of tyrosine with horseradish peroxidase and lactoperoxidase. Biochem J... 

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