Disease relevance of LPO

• Antibacterial effect of lactoperoxidase and myeloperoxidase against Bacillus cereus [1].
• PCR cloning and baculovirus expression of human lactoperoxidase and myeloperoxidase [2].
• In addition, the airway LPO system was shown to be effective against Burkholderia cepacia and Haemophilus influenzae [3].
• Finally, as expected based on the known antibacterial spectrum of the LPO system, airway secretions showed LPO-dependent activity against Pseudomonas aeruginosa [3].
• Glucose oxidase and peroxidase (lactoperoxidase or myeloperoxidase) are virucidal to human immunodeficiency virus type 1 (HIV-1) in the presence of sodium iodide, as assessed by the loss of viral replication in a syncytium-forming assay or by the inhibition of cytopathic effects on infected cells [4].

Psychiatry related information on LPO

• Lactoperoxidase belongs to the natural defense mechanisms of the oral cavity [5].

High impact information on LPO

• Chloro- and myeloperoxidases catalyze oxidation of all halide ions, except F-; oxidation of bromide and iodide is mediated by lactoperoxidase, but horseradish peroxidase only oxidizes iodide [6].
• It is a cell-surface macromolecule (labelled with 125I and lactoperoxidase) which, in its isolated state, retains the ability to bind both C3 and C3b [7].
• Similar effects were observed after treatment of the axon with tetranitromethane or after iodination with lactoperoxidase [8].
• This inference is supported by experimental results on the Coprinus macrorhizus peroxidase (52), manganese peroxidase (51), lignin peroxidase (50) and, less definitively, lactoperoxidase (90) [9].
• In contrast, 3-chlorotyrosine was undetectable in LDL oxidized by hydroxyl radical, copper, iron, hemin, glucose, peroxynitrite, horseradish peroxidase, lactoperoxidase, or lipoxygenase [10].

Chemical compound and disease context of LPO

• Therefore, we analyzed both immune (total IgA, IgG, IgM, anti-Streptococcus mutans IgA, IgG, and IgM antibodies) and nonimmune (lysozyme, lactoferrin, salivary peroxidase, myeloperoxidase, hypothiocyanite, thiocyanate, and agglutinins) factors in whole saliva of 15 patients with common variable immunodeficiency [11].
• Placental concentrations of LPO, MDA and ascorbic acid were not significantly different in pre-eclampsia as compared with normal pregnancy [12].
• We investigated the reactivity of LPO towards five molecules: 17-beta-estradiol (a natural hormone), diethylstilbestrol (a synthetic drug, supplied to pregnant women for preventing spontaneous abortion), exestrol (a synthetic antigonadotropic estrogen), 2-OH- and 4-OH-estradiol (catabolic products of estradiol) [13].
• The antibodies against acetylcholine receptor AchR and levels of SOD and LPO were measured in 11 patients with myasthenia gravis (MG), and the results were compared with normal controls and patients with diseases other than MG [14].
• We have studied the surface exposed membrane proteins of human acute myeloid leukemia cells employing the lactoperoxidase, periodate, or the neuraminidase/galactose oxidase ectolabeling procedures [15].

Biological context of LPO

• Mechanistic implications are discussed in relation to LPO and myeloperoxidase, an enzyme present in neutrophils and monocytes which contains a unique functional active-site chlorin [16].
• The amino acid sequence of human LPO has 51% similarity with those of both human MPO and EPO, suggesting that these peroxidase genes have evolved from a common ancestral gene [17].
• Our results demonstrate that the EPX, LPO, and MPO genes form a cluster on human chromosome 17 [18].
• Here we show that the human EPX gene maps to chromosome 17q23.1, which localizes 34 kb from the LPO and MPO genes [18].
• The evidence for this mechanism includes irreversible, hydrogen peroxide-dependent loss of enzymatic activity by kinetics consistent with a suicide mechanism, concomitant with changes in the visible spectrum of the prosthetic heme group and covalent binding of resorcinol (ca. 10 mol/mol of lactoperoxidase inactivated) [19].

Anatomical context of LPO

• Lactoperoxidase (LPO) is an oxidoreductase secreted into milk, and plays an important role in protecting the lactating mammary gland and the intestinal tract of the newborn infants against pathogenic microorganisms [17].
• When the minigene comprised of exon 11, intron 11 and exon 12 of the human LPO gene was introduced into COS cells, the correct splicing of the intron was found, suggesting the intron 11 of the human LPO gene is functional [17].
• These results provide evidence that LPO is present in mature human milk and that it is responsible for most of the peroxidase activity in mature milk [20].
• (32)P-post-labelling analysis showed that IQ-DNA adducts were formed after co-incubation of IQ (500 microM) with calf thymus DNA, hydrogen peroxide and either bovine LPO or horseradish peroxidase (HRP) [21].
• Myeloperoxidase (MPO) belongs to a family of related proteins which also includes eosinophil, thyroid, and lactoperoxidase [22].

Associations of LPO with chemical compounds

• Rapid kinetic measurements indicate that MPO, EPO, and LPO Compound I formation occur at rates slower than complex decay, and its formation serves to simultaneously catalyze SCN- via 1e- and 2e- oxidation pathways [23].
• The species with a nonderivatized methyl group was not found among LPO peptides [24].
• In contrast, LPO Compound II is unstable and decays within seconds to ground state, suggesting that SCN- may serve as a substrate for Compound II [23].
• These results provide an explanation for the potency of resorcinol derivatives in the inhibition of LPO and TPO and the goitrogenic responses observed in humans and animals [19].
• Whey from early milk was fractionated into two peaks of peroxidase activity by cation-exchange chromatography; the peroxidase in the first peak was sensitive to dapsone, which is an inhibitor of LPO, whereas the second peroxidase was not [20].

Physical interactions of LPO

• When the LPO- and CT-125I-C1q-binding patterns obtained on serum samples from patients with systemic lupus erythematosus, rheumatoid arthritis, or essential mixed cryoglobulinaemia were compared with binding patterns observed using laboratory reactants, an immediate detection of non-immune-aggregate-mediated C1q binding became possible [25].
• Asialoorosomucoid was conjugated to lactoperoxidase and bound specifically to the asialoglycoprotein receptor on the human cell line Hep G2 at 4 degrees C. The bound conjugates incorporated 125I into cell surface proteins in the presence of H2O2 [26].

Enzymatic interactions of LPO

• Myeloperoxidase will catalyse the peroxidation of the chloride ion but salivary peroxidase will not; the product of this in neutral solution is the hypochlorite ion, which is also a reactive oxidizing agent [27].
• Kinetics of the iodination and the coupling reaction in thyroglobulin catalyzed by lactoperoxidase and chloramine T [28].

Co-localisations of LPO

• Our results indicated that the cytoplasmic form of CD22 comigrated with 125I/lactoperoxidase-labeled surface CD22 [29].

Regulatory relationships of LPO

• At pH 5.5 LP activity was inhibited by 85% and MP by 34% with 10 mM F-. TSP activity was also inhibited only at low pH (5.5) by approximately 25% [30].
• High concentrations of CP inhibited LPO [31].
• Further extension of the basic model by inclusion of a hypothetical antioxidant leads to a model which is capable of describing Cu(2+)-induced LPO over the whole lag phase up to full propagation [32].

Other interactions of LPO

• Mechanism-based inactivation of lactoperoxidase and thyroid peroxidase by resorcinol derivatives [19].
• Using NO-selective electrodes and direct spectroscopic and rapid kinetic methods, we examined the interactions of NO with EPO and LPO compounds I and II and ferric forms and compared the results to those reported for myeloperoxidase [33].
• Lysozyme, lactoferrin, salivary peroxidase, myeloperoxidase, and thiocyanate concentrations were determined from both whole saliva and parotid saliva [34].
• Studies with purified enzymes have shown that CN- also stimulates NADPH oxidation by horseradish peroxidase or lactoperoxidase, suggesting that the respiratory burst might be initiated by activation of a peroxidase-like enzyme in the human polymorphonuclear leukocyte [35].
• These compounds were compared by their electrochemical potentials as well as their oxidative lability in the presence of several oxidative enzyme systems (i.e., horseradish peroxidase, lactoperoxidase, myeloperoxidase, and diamine oxidase) [36].

Analytical, diagnostic and therapeutic context of LPO

• In this study, we amplified genes encoding LPO and MPO from human mammary gland cDNA by the polymerase chain reaction (PCR) [2].
• In this study, we replaced Asp-96 in MPO and the counterpart Asp-227 in LPO both with Ala by site-directed mutagenesis [37].
• Genomic sequence analysis revealed that the mouse LPO gene has similar genomic organization to the corresponding human gene [38].
• Molecular cloning and characterization of the chromosomal gene for human lactoperoxidase [17].
• The data showed that normal human airway secretions contained LPO enzyme activity (0.65 +/- 0.09 microg/mg secreted protein; n = 17), and Western blots of secretions demonstrated bands of the expected sizes for LPO [3].

References