PRKN and Parkinson disease: Overproduction of NO has been shown to result in neuronal damage and may be associated with S-nitrosylation or nitration of certain important proteins, including the S-nitrosylation of Parkin (41,42), protein-disulphide isomerase (43), mitochondrial complex I (44), peroxiredoxin-2 (45) and the nitration of α-synuclein (46) in the neurodegenerative process of PD.