| Lactoperoxidase (LPO) is a glycoprotein with a hemin prosthetic group occurring as a mixture of 2 isoenzymes. It has a molecular weight of 77,500 daltons. LPO catalyzes the hydrogen peroxide oxidation of iodide according to the following reaction: 2I- + H2O2 + 2H+ I2 + 2H2O Iodide reacts directly with the heme group, upon addition of H2O2 the complex iodinates the substrate. LPO is inhibited by hydrazines. The 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. Specific Activity: 35units/mg dry weight (lot-specific) Unit Definition of Activity: One unit reduces one micromole of hydrogen peroxide per minute at 25C, pH 6.0. The assay procedure is a modification of the method described by Putter and Becker (Meth. Enz. Anal., III, 286 (1983). The increase in the absorbance at 405nm resulting from the oxidation of ABTS diammonium salt is determined. Two moles of ABTS are oxidized for every mole of peroxide that is reduced. Storage and Stability: Lyophilized powder may be stored at -20C. Stable for 12 months at -20C. Reconstitute with sterile ddH2O. Aliquot to avoid repeated freezing and thawing. Store at -20C. Reconstituted product is stable for 6 months at -20C. 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. Certificate 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. |
