Lactoperoxidase is a candidate for mediating neuromelanin formation in the human substantia nigra

The presence of neuromelanin is a characteristic feature of the human substantia nigra (SN); however, the mechanism of its synthesis and its role in the development of Parkinson’s disease remain unclear. Here, we report that the host defense enzyme lactoperoxidase (LPO), which possesses broad antimicrobial activity on mucosal surfaces, is selectively expressed in human dopaminergic neurons, a feature not shared by the rodent SN. We also demonstrate that LPO can catalyze multiple steps of melanin