A THEORETICAL 3-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 haloperoxidases, a group of mammalian en zymes able to catalyze the peroxidative oxidation of halides and pseud ohalides, such as thiocyanate. They all play a key role in the develop ment of antibacterial activity. The homology in their functional role is emphasized by the striking similarity of their primary structures. A theoretical model for the three-dimensional structure of LPO and EPO has been developed on the basis of the X-ray structure of MPO, a high degree of similarity having been found in their sequences. Evidence s upporting the hypothesis of an ester linkage between heme and apoprote in in LPO and EPO, originally proposed by Hultquist and Morrison is di scussed.