Parkinson's disease (PD) is a common neurodegenerative disorder characterized by impairment in motor function. PD is mostly sporadic, but rare familial cases are also found. The exact pathogenic mechanism is not fully understood, but both genetic and environmental factors are known to be important contributors. In particular, oxidative stress mediated through nitric oxide (NO) is believed to be a prime suspect in the development of PD. NO can exert its effect by modifying different biological molecules, and one of these modifications is through S-nitrosylation. Because of the liable nature of S-nitrosylation, a number of methods are often used to study this modification. We have successfully employed some of these methods and showed that a familial related protein, parkin, can be S-nitrosylated and provide a common pathogenic mechanism for sporadic and familial PD.