Lactoperoxidase is a peroxidase enzyme found in milk. It is able to form reactive bromine and iodine species, resulting in natural organobromine and organoiodine substances, and can therefore be categorised as a haloperoxidase. It is fairly heat resistant and was widely used as an indicator of overpasteurization of milk.Freshly isolated and purified samples of goat LPO were saturated with ammonium iodide and crystallized using 20% polyethylene glycol 3350 in a hanging drop vapor diffusion setup. The structure has been determined using X-ray crystallographic method. Goat LPO consists of a single polypeptide chain of 595 amino acid residues and folds into an oval-shaped structure. The structure contains 20 well-defined alpha-helices of varying lengths including a helix, H(2a), unique to LPO, and two short antiparallel beta-strands.