A theoretical three-dimensional model for lactoperoxidase and eosinophil peroxidase built on the scaffold of the myeloperoxidase X-ray structure

Lactoperoxidase (LPO), eosinophil peroxidase (EPO) and myeloperoxidase (MPO) belong to the class of haloperoxidase, a group of mammalian enzymes able to catalyze the peroxidative oxidation of halide and pseudohalide, like thiocyanate. They all play a key role in the development of antibacterial activity, whereas the homology in functional role is emphasized by the striking similarity of their primary structures. A theoretical model for the tridimensional structure of LPO and EPO has been elaborated on the basis of MPO X-ray structure, on account of the high degree of similarity found in their sequences. Some evidences supporting the hypothesis of an ester-linkage between heme and apoprotein in LPO and EPO, originally proposed by Hultquist & Morrison [J. Biol. Chem. (1963) 238, 2843-46], are discussed.