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Gene Review

LPO  -  lactoperoxidase

Homo sapiens

Synonyms: Lactoperoxidase, SAPX, SPO, Salivary peroxidase
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Disease relevance of LPO


Psychiatry related information on LPO


High impact information on LPO


Chemical compound and disease context of LPO


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


Co-localisations of LPO


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


Analytical, diagnostic and therapeutic context of LPO


  1. Antibacterial effect of lactoperoxidase and myeloperoxidase against Bacillus cereus. Tenovuo, J., Mäkinen, K.K., Sievers, G. Antimicrob. Agents Chemother. (1985) [Pubmed]
  2. PCR cloning and baculovirus expression of human lactoperoxidase and myeloperoxidase. Shin, K., Hayasawa, H., Lönnerdal, B. Biochem. Biophys. Res. Commun. (2000) [Pubmed]
  3. Lactoperoxidase and human airway host defense. Wijkstrom-Frei, C., El-Chemaly, S., Ali-Rachedi, R., Gerson, C., Cobas, M.A., Forteza, R., Salathe, M., Conner, G.E. Am. J. Respir. Cell Mol. Biol. (2003) [Pubmed]
  4. Virucidal effects of glucose oxidase and peroxidase or their protein conjugates on human immunodeficiency virus type 1. Yamaguchi, Y., Semmel, M., Stanislawski, L., Strosberg, A.D., Stanislawski, M. Antimicrob. Agents Chemother. (1993) [Pubmed]
  5. Xylitol-induced increase of lactoperoxidase activity. Mäkinen, K.K., Tenovuo, J., Scheinin, A. J. Dent. Res. (1976) [Pubmed]
  6. Peroxidase-catalyzed halogenation. Morrison, M., Schonbaum, G.R. Annu. Rev. Biochem. (1976) [Pubmed]
  7. Isolation of a biologically active macrophage receptor for the third component of complement. Schneider, R.J., Kulczycki, A., Law, S.K., Atkinson, J.P. Nature (1981) [Pubmed]
  8. Sodium channel inactivation in squid axon is removed by high internal pH or tyrosine-specific reagents. Brodwick, M.S., Eaton, D.C. Science (1978) [Pubmed]
  9. Catalytic sites of hemoprotein peroxidases. Ortiz de Montellano, P.R. Annu. Rev. Pharmacol. Toxicol. (1992) [Pubmed]
  10. 3-Chlorotyrosine, a specific marker of myeloperoxidase-catalyzed oxidation, is markedly elevated in low density lipoprotein isolated from human atherosclerotic intima. Hazen, S.L., Heinecke, J.W. J. Clin. Invest. (1997) [Pubmed]
  11. Salivary defense factors and oral health in patients with common variable immunodeficiency. Kirstilä, V., Tenovuo, J., Ruuskanen, O., Nikoskelainen, J., Irjala, K., Vilja, P. J. Clin. Immunol. (1994) [Pubmed]
  12. Oxidative stress in pre-eclampsia. Bowen, R.S., Moodley, J., Dutton, M.F., Theron, A.J. Acta obstetricia et gynecologica Scandinavica. (2001) [Pubmed]
  13. Can estrogenic radicals, generated by lactoperoxidase, be involved in the molecular mechanism of breast carcinogenesis? Ghibaudi, E.M., Laurenti, E., Beltramo, P., Ferrari, R.P. Redox Rep. (2000) [Pubmed]
  14. Clinical measurement of antibodies against acetylcholine receptor (AchR), SOD and LPO in patients with myasthenia gravis (MG) before and after thymectomy. Pan, T.C., Yang, M.S., Cao, X.B., Ge, Y.X., Zhang, B.G., Zhao, J.P., Cheng, X.F. J. Tongji Med. Univ. (1994) [Pubmed]
  15. Two-dimensional membrane protein patterns of acute myeloid leukemia cells and mature myeloid cells after various ectolabeling procedures. de Jong, J.G., Dekker, A.W., Kapteijn, R., Sixma, J.J. Blood (1984) [Pubmed]
  16. Resonance Raman characterization of the heme prosthetic group in eosinophil peroxidase. Sibbett, S.S., Klebanoff, S.J., Hurst, J.K. FEBS Lett. (1985) [Pubmed]
  17. Molecular cloning and characterization of the chromosomal gene for human lactoperoxidase. Ueda, T., Sakamaki, K., Kuroki, T., Yano, I., Nagata, S. Eur. J. Biochem. (1997) [Pubmed]
  18. The eosinophil peroxidase gene forms a cluster with the genes for myeloperoxidase and lactoperoxidase on human chromosome 17. Sakamaki, K., Kanda, N., Ueda, T., Aikawa, E., Nagata, S. Cytogenet. Cell Genet. (2000) [Pubmed]
  19. Mechanism-based inactivation of lactoperoxidase and thyroid peroxidase by resorcinol derivatives. Divi, R.L., Doerge, D.R. Biochemistry (1994) [Pubmed]
  20. Identification of lactoperoxidase in mature human milk. Shin, K., Tomita, M., Lönnerdal, B. J. Nutr. Biochem. (2000) [Pubmed]
  21. Pathways of heterocyclic amine activation in the breast: DNA adducts of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) formed by peroxidases and in human mammary epithelial cells and fibroblasts. Williams, J.A., Stone, E.M., Millar, B.C., Hewer, A., Phillips, D.H. Mutagenesis (2000) [Pubmed]
  22. Molecular genetics of peroxidase deficiency. Petrides, P.E. J. Mol. Med. (1998) [Pubmed]
  23. Thiocyanate modulates the catalytic activity of mammalian peroxidases. Tahboub, Y.R., Galijasevic, S., Diamond, M.P., Abu-Soud, H.M. J. Biol. Chem. (2005) [Pubmed]
  24. Biochemical evidence for heme linkage through esters with Asp-93 and Glu-241 in human eosinophil peroxidase. The ester with Asp-93 is only partially formed in vivo. Oxvig, C., Thomsen, A.R., Overgaard, M.T., Sorensen, E.S., Højrup, P., Bjerrum, M.J., Gleich, G.J., Sottrup-Jensen, L. J. Biol. Chem. (1999) [Pubmed]
  25. An extended C1q-binding assay using lactoperoxidase- and chloramine-T-iodinated C1q. Immediate distinction between immune-aggregate-mediated and non-immune-aggregate-mediated C1q binding. Spaeth, P.J., Corvetta, A., Nydegger, U.E., Montroni, M., Buetler, R. Scand. J. Immunol. (1983) [Pubmed]
  26. In situ 125I-labelling of endosome proteins with lactoperoxidase conjugates. Watts, C. EMBO J. (1984) [Pubmed]
  27. Specific assays for peroxidases in human saliva. Mansson-Rahemtulla, B., Baldone, D.C., Pruitt, K.M., Rahemtulla, F. Arch. Oral Biol. (1986) [Pubmed]
  28. Kinetics of the iodination and the coupling reaction in thyroglobulin catalyzed by lactoperoxidase and chloramine T. Lamas, L. Eur. J. Biochem. (1979) [Pubmed]
  29. Expression and structure of CD22 in acute leukemia. Boué, D.R., LeBien, T.W. Blood (1988) [Pubmed]
  30. Fluoride inhibits the antimicrobial peroxidase systems in human whole saliva. Hannuksela, S., Tenovuo, J., Roger, V., Lenander-Lumikari, M., Ekstrand, J. Caries Res. (1994) [Pubmed]
  31. Promotion of glutathione-gamma-glutamyl transpeptidase-dependent lipid peroxidation by copper and ceruloplasmin: the requirement for iron and the effects of antioxidants and antioxidant enzymes. Glass, G.A., Stark, A.A. Environ. Mol. Mutagen. (1997) [Pubmed]
  32. Simulation of lipid peroxidation in low-density lipoprotein by a basic "skeleton" of reactions. Abuja, P.M., Esterbauer, H. Chem. Res. Toxicol. (1995) [Pubmed]
  33. Peroxidases inhibit nitric oxide (NO) dependent bronchodilation: development of a model describing NO-peroxidase interactions. Abu-Soud, H.M., Khassawneh, M.Y., Sohn, J.T., Murray, P., Haxhiu, M.A., Hazen, S.L. Biochemistry (2001) [Pubmed]
  34. Salivary defense mechanisms in juvenile periodontitis. Saxén, L., Tenovuo, J., Vilja, P. Acta Odontol. Scand. (1990) [Pubmed]
  35. Effect of cyanide on NADPH oxidation by granules from human polymorphonuclear leukocytes. DeChatelet, L.R., McPhail, L.C., Shirley, P.S. Blood (1977) [Pubmed]
  36. A proposed mechanism for p-aminoclonidine allergenicity based on its relative oxidative lability. Thompson, C.D., Vachaspati, P.R., Kolis, S.P., Gulden, P.H., Garst, M.E., Wiese, A., Munk, S.A., Harman, W.D., Macdonald, T.L. Chem. Res. Toxicol. (1997) [Pubmed]
  37. Mutations affecting the calcium-binding site of myeloperoxidase and lactoperoxidase. Shin, K., Hayasawa, H., Lönnerdal, B. Biochem. Biophys. Res. Commun. (2001) [Pubmed]
  38. The evolutionary conservation of the mammalian peroxidase genes. Sakamaki, K., Ueda, T., Nagata, S. Cytogenet. Genome Res. (2002) [Pubmed]
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