Lactoperoxidase (LPO, EC 1.11.1.7)

A glycoprotein with a hemin prosthetic group occurring as a mixture of 2 isoenzymes. Lactoperoxidase (LPO) catalyzes the hydrogen peroxide oxidation of iodide. It has a molecular weight of 77,500 daltons. LPO catalyzes the hydrogen peroxide oxidation of iodide according to the following reaction:\n2I- + H2O2 + 2H+ ? I2 + 2H2O.\n\nIodide reacts directly with the heme group; upon addition of H2O2 the complex iodinates the substrate. LPO is inhibited by hydrazines. The assay procedure has been updated from that of Morrison to an ABTS(R)/H2O2 based method with increased sensitivity and reproducibility.\n\nUnit Definition: One Unit reduces one micromole of hydrogen peroxide per minute at 25 degrees C, pH 6.0. Note: This unit definition is based upon a new assay method. The previous method yielded approximately 2.8 times higher results.\n\nThe bovine milk enzyme is identical to that formed in bovine lacrimal and salivary glands. LPO may be important in controlling bacterial flora and is useful for labeling proteins with radioiodine. For membrane studies, the large LPO molecule limits labeling to the exposed surface.\n\nStorage and Stability: Lyophilized powder may be stored at -20 degrees C. Stable for 12 months at -20 degrees C. Reconstitute with sterile ddH2O. Aliquot to avoid repeated freezing and thawing. Store at -20 degrees C. Reconstituted product is stable for 6 months at -20 degrees C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.\n\nCertificate of Origin: The raw animal product (bovine milk) used in the manufacturing of Lactoperoxidase is of North American origin, where there have been no reported cases of bovine spongiform encephalopathy (BSE), and obtained from United States Department of Agriculture (USDA) approved facilities, inspected and certified to be free of disease and suitable for human consumption and/or exportation. All slaughtered animals are given ante and post-mortem inspections and those that are found to be wholesome are passed for human consumption. All manufacturing and purification takes place at facilities located in the USA.

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SPECIFICATIONS

Catalog Number

L1024

Size

10mg

Form

Supplied as a lyophilized powder.

References

1. Allen, P., and Morrison, M (1963) Biochem. Biophys., 102:106. 2. Allison, W., et al., (1973) Biochem. Biophys., 155:400. 3. Arntzen, C., et al., (1974) Biochim. Biophys. Acta, 347:329. 4. Bayse, G., et al., (1972) Biochim. Biophys. Acta, 284:30. 5. Bjorck, L., et al., (1975) Microbiol., 30:199. 6. Chung, J., et al., (1970) Biochem. Biophys., 141:73. 7. David, G. (1972)Biophys. Res. Comm., 48:464. 8. David, G., et al., (1974) Biochem., 13:1014. 9. David, G., et al., (1974) Science, 184:1381. 10. Doerge, D.: Oxygenation of Organosulfur Compounds by Peroxidation: Evidence of an Electron Transfer Mechanism for Lactoperoxidase, Arch. Biochem. Biophys., 244, 678 (1986). 11. Dolman, D., Dunford, H., Chowdhury, D., and Morrison, M.: The Kinetics of Cyanide Binding by Lactoperoxidase, Biochem., 7, 3991 (1968). 12. Frantz, W., and Turkington, R.: Formation of Biologically Active 125I-Prolactin by Enzymatic Radioiodination, Endocrin., 91, 1545 (1972). 13. Gothefors, L., and Marklund, S.: Lactoperoxidase Activity in Human Milk and in Saliva of Newborn Infants, Infect. Immun., 11, 1210 (1975). 14. Gow, J., and Wardlaw, A.: Iodination of a Mixture of Soluble Proteins by 125I-Lactoperoxidase Technique, Biochem. Biophys. Res. Comm., 67, 43 (1975). 15. Haustein, D.: Effective Radioiodination by Lactoperoxidase and Solubilization of Cell-Surface Proteins of Cultured Murine T Lymphoma Cells, J. Imm. Meth., 7, 25 (1975). 16. Hildebrandt, G., and Aronson, N.: Endocytosis of Bovine Lactoperoxidase by Two Carbohydrate-Specific Receptors in Rat Liver, Arch. Biochem. Biophys., 237, 1 (1985). 17. Hogg, N.: A Comparison of Membrane Proteins of Normal and Transformed Cells by Lactoperoxidase Labeling, Proc. Natl. Acad. Sci. USA, 71, 489 (1974). 18. Holohan, K., Murphy, R., Buchanan, K., and Elmore, D.: Enzymatic Iodination of Polypeptide Hormones for Radioimmunoassay, Clin. Chim. Acta, 45, 153 (1973). 19. Huber, C., Edwards, H., and Morrison, M.: The Effect of Lactoperoxidase-Catalyzed Iodination on the Integrity of Mitochondrial Membranes, Arch. Biochem. Biophys., 168, 463 (1975). 20. Hultquist, D., and Morrison, M.: Lactoperoxidase. I. The Prosthetic Group of Lactoperoxidase, J. Biol. Chem., 238, 2843 (1963). 21. Huwiler, M., and Kohler, H.: Pseudo-catalytic Degradation of Hydrogen Peroxide in the Lactoperoxidase/H2O2/Iodide System, Eur. J. Biochem., 141, 69 (1984). 22. Huwiler, M., Jenzer, H., and Kohler, H.: The Role of Compound III in Reversible and Irreversible Inactivation of Lactoperoxidase, Eur. J. Biochem., 158, 609 (1986). 23. Johnson, D., Thorton, D., and Ryan, P.: Lactoperoxidase Immobilization on Inorganic Supports, Biochem. Soc. Trans., 2, 494 (1975). 24. Jone, C., and Hager, L.: Iodination of Zeta Protein by Lactoperoxidase, Chloroperoxidase and Chloramine T, Biochem. Biophys. Res. Comm., 68, 16 (1976). 25. Karonen, S., Morsky, P., Siren, M., and Seuderling, V.: An Enzymatic Solid-Phase Method for Trace Iodination of Proteins and Peptides with 125 Iodine, Anal. Biochem., 67, 1 (1975). 26. Kitagawa, T., Hashimoto, S., Teraoka, J., Nakamura, S., Yajima, H., and Hosoya, T.: Distinct Heme-Substrate Interactions of Lactoperoxidase Probed by Resonance Raman Spectroscopy: Difference between Animal and Plant Peroxidases, Biochem., 22, 2788 (1983). 27. Lamas, L.: Kinetics of the Iodination and the Coupling Reaction in Thyroglobulin Catalyzed by Lactoperoxidase and Chloramine T, Eur. J. Biochem., 96, 93 (1979). 28. Maguire, R., and Dunford, H.: The Kinetics of the Formation of the Primary Lactoperoxidase-Hydrogen Peroxide Compound, Can. J. Biochem., 49, 1165 (1971). 29. Maguire, R., and Dunford, H.: Kinetics of the Oxidation of Iodine Ion by Lactoperoxidase Compound II, Biochem. 11, 937 (1972). 30. Marchalonis, J.: An Enzymic Method for the Trace Iodination of Immunoglobulins and Other Proteins, Biochem. J., 113, 299 (1969). 31. McIlhinney, J., and Schulster, D.: The Preparation of Biologically Active 125I-Labelled Adrenocorticotropic Hormone by a Simple Enzymic Radioiodination Procedure Utilizing Lactoperoxidase, Endocrin., 94, 1259 (1974). 32. Morrison, M.: Iodination of Tyrosine: Isolation of Lactoperoxidase (Bovine), in Methods in Enzymology, XVIIA, (Tabor, H., and Tabor, C., eds.,), Academic Press, NY, 653 (1970). 33. Morrison, M., Allen, P., Bright, J., and Jayasinghe, W.: Lactoperoxidase. V. Identification and Isolation of Lactoperoxidase from Salivary Gland, Arch. Biochem. Biophys., 111, 126 (1965). 34. Morrison, M., and Allen, P.: The Identification and Isolation of Lactoperoxidase from Salivary Gland, Biochem. Biophys. Res. Comm., 13, 490 (1963). 35. Morrison, M., and Allen, P.: Lactoperoxidase: Identification and Isolation of Lactoperoxidase from Harderian and Lacrimal Glands, Science, 152, 1626 (1966). 36. Morrison, M., and Bayse, G.: Catalysis of Iodination by Lactoperoxidase, Biochem., 9, 2995 (1970). 37. Morrison, M., and Bayse, G.: Stereospecificity in Peroxidase-Catalyzed Reaction, in Oxidases and Related Redox Systems, Vol. I, (King, T., Mason, H., and Morrison, M., eds.), Univ. Pk. Press, Baltimore, 375 (1973). 38. Morrison, M., and Hultquist, D.: Lactoperoxidase. II. Isolation, J. Biol. Chem., 238, 2847 (1963). 39. Morrison, M., Hamilton, H., and Stotz, E.: The Isolation and Purification of Lactoperoxidase by Ion Exchange Chromatography, J. Biol. Chem., 228, 767 (1957). 40. Nachman, R., Hubbard, A., and Ferris, B.: Iodination of the Human Platelet Membrane. Studies of the Major Surface Glycoprotein, J. Biol. Chem., 248, 2928 (1973). 41. Ohlsson, P.: Lactoperoxidase, a Dithionite Ion Dismutase, Eur. J. Biochem., 142, 233 (1984). 42. Phillips, D., and Morrison, M.: Exposed Protein on the Intact Human Erythrocyte, Biochem., 10, 1767 (1971). 43. Poduslo, J., and Braun, P.: Topographical Arrangement of Membrane Proteins in the Intact Myelin Sheath. Lactoperoxidase Incorporation of Iodine into Myelin Surface Proteins, J. Biol. Chem., 250, 1099 (1975). 44. Polis, B., and Shmukler, H.: Crystalline Lactoperoxidase. I. Isolation by Displacement Chromatography. II. Physicochemical and Enzymatic Properties, J. Biol. Chem., 201, 475 (1953). 45. Pommier, J., and Cahnmann, H.: Interaction of Lactoperoxidase with Thiols and Diiodotyrosine, J. Biol. Chem., 254, 3006 (1979). 46. Rombauts, W., Schroeder, W., and Morrison, M.: Bovine Lactoperoxidase. Partial Characterization of the Further Purified Protein, Biochem., 6, 2965 (1967). 47. Shin, B., and Carraway, K.: Lactoperoxidase Labelling of Erythrocyte Membranes from the Inside and Outside, Biochim. Biophys. Acta, 345, 141 (1974)

Alternative Names

LPO, E.C. 1.11.1.7