Disease relevance of LPO

• A baculovirus expression system has been developed for LPO and used to obtain protein in which the heme is only partially covalently bound [1].
• In the present study, the effects of orally administered LF and LPO were assessed in a mouse influenza virus infection model [2].
• A study of the time-course of LDL oxidation showed that the toxicity of Ox-LDL depends upon the level of LPO, not upon the content of TBARS, the extent of negative charge or the protein adduct of aldehydes [3].
• Glucose oxidase (GOD) as a source of hydrogen peroxide for the lactoperoxidase (LPO) system in milk: antibacterial effect of the GOD-LPO system against mastitis pathogens [4].

High impact information on LPO

• Heme reduction of ferric lactoperoxidase (LPO) into its ferrous form initially leads to the accumulation of the unstable form of LPO-Fe(II), which spontaneously converts to a more stable species, the two of which can be identified by Soret peaks at 440 and 434 nm, respectively [5].
• The monomeric protein recovered from incubations of LPO with H(2)O(2) is fully active but no longer forms dimers when incubated with H(2)O(2), clear evidence that it has also been structurally modified [6].
• Proteolytic digestion and mass spectrometric analysis indicates that the dimer is held together by a dityrosine link between Tyr-289 in each of two LPO molecules [6].
• We report here that LPO reacts with the spin trap 3,5-dibromo-4-nitroso-benzenesulfonic acid to give a 1:1 protein-bound radical adduct [6].
• Analysis of the interface in the LPO dimers indicates that the same protein surface is involved in LPO dimerization as in the normal formation of myeloperoxidase dimers [6].

Biological context of LPO

• The covalently bound prosthetic group of lactoperoxidase (LPO) has been obtained by hydrolysis of the protein and identified as a dihydroxylated heme [1].
• The recombinant LPO was secreted as an enzymatically active single chain molecule presenting two immunoreactive forms of 88 kDa and 82 kDa, differing by their glycosylation. rLPO exhibited the characteristic absorbance spectrum with a Soret peak at 413 nm [7].
• We suggest that indomethacin interacts at the aromatic donor binding site and is oxidised by one-electron transfer by LPO catalytic intermediates to stable oxidation product(s) through the formation of a free radical [8].
• The rate constant of dioxygen dissociation from compound III is higher than conversion of compound III to ferric LPO, which is not affected by the oxygen concentration and follows a biphasic kinetics [9].
• At atmospheric pressure, inactivation of lactoperoxidase (LPO) in milk and whey was studied in a temperature range of 69-73 degrees C and followed first order kinetics [10].

Anatomical context of LPO

• The LPO results provide a paradigm for autocatalytic incorporation of heme groups into the mammalian peroxidases, including myeloperoxidase and eosinophil peroxidase, all of which exhibit strong sequence similarity with LPO and have covalently-bound heme groups [1].
• The cDNA encoding bovine lactoperoxidase (LPO) has been expressed in CHO cells [7].
• In contrast to this paradigm, new data suggest that LPO and other substances are retained at the ciliary border of the airway epithelium by binding to surface-associated hyaluronan, thereby providing an apical, fully active enzyme pool [11].
• Among many antimicrobial substances, mucus contains a peroxidase identical to milk lactoperoxidase (LPO) that is produced by goblet cells and submucosal glands [11].

Associations of LPO with chemical compounds

• The oxidation of thiocyanate by H2O2 in the presence of LPO does not take place at pH greater than 8 [12].
• Characterization of the low-spin LPO/NO2- complex by EPR and visible spectroscopy is reported [13].
• For the v10 band, benzohydroxamic acid caused a frequency shift with HRP but not with LPO [14].
• Guaiacol, o-toluidine, and histidine brought about a frequency shift of the v4 mode for LPO but not for HRP [14].
• The formation of hypothiocyanite ion (OSCN-) as one of the oxidation products correlated well with the activity of the LPO/SCN-/H2O2 system and was maximum when the concentrations of the H2O2 and SCN- were nearly the same and the pH was less than 6 [12].

Other interactions of LPO

• Highly purified porcine TPO was compared with lactoperoxidase (LPO) and chloroperoxidase (CPO) for ability to catalyze bromination of tyrosine, thyroglobulin, and bovine serum albumin (BSA) [15].
• Furthermore, electron paramagnetic resonance has played a fundamental role in evaluating the enzyme purity against lactoferrin and minor LPO isoenzyme components in setting the final steps of the purification [16].
• Rapid communication: detection and mapping of polymorphisms in the bovine Lactoperoxidase (LPO) gene and in the Glycosylation-dependent cell adhesion molecule 1 (GlyCAM1) gene using fluorescent single-strand conformation polymorphism analysis [17].

Analytical, diagnostic and therapeutic context of LPO

• Lactoperoxidase (LPO) was purified from bovine milk using Amberlite CG 50 H+ resin, CM Sephadex C-50 ion-exchange chromatography, and Sephadex G-100 gel filtration chromatography [18].

References