Peroxidative aggregation of α‐synuclein requires tyrosines

α‐Synuclein is the main component of the intracellular protein aggregates in neurons of patients with Parkinson's disease. The occurrence of the disease is associated with oxidative damage. Although it is known that peroxidative chemistry leads to the aggregation of α‐synuclein in vitro, the specific amino acid types of α‐synuclein involved in this type of aggregation have not been identified. We show, using human cytochrome c plus H₂O₂ as the source oxidative stress, that the tyrosines of α‐synuclein are required for aggregation. The studies reveal the chemical basis for a crucial step in the aggregation process.