Abstract
Protein tyrosine nitration is a post-translational modification associated with conditions of oxidative and inflammatory stress, driven by the production of reactive oxygen and nitrogen species (ROS and RNS). Once considered primarily a footprint of oxidative damage, tyrosine nitration is increasingly recognized as a selective modification that, in specific biological contexts, can alter protein structure, stability, enzymatic activity, and interaction networks. Mechanistically, nitration occurs through peroxynitrite-dependent and heme-peroxidase-dependent pathways and preferentially targets specific tyrosine residues based on local protein structure, solvent accessibility, and microenvironmental chemistry. Accumulating evidence has identified disease-specific nitration signatures across multiple pathological contexts. In neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, nitration of proteins such as tau, α-synuclein, manganese superoxide dismutase, ATP synthase, glyceraldehyde-3-phosphate dehydrogenase, heat shock proteins, and cytoskeletal components contributes to mitochondrial dysfunction, protein aggregation, metabolic failure, and neuronal loss. Similarly, in cardiovascular and pulmonary diseases, protein tyrosine nitration disrupts vascular and epithelial homeostasis by impairing endothelial signaling, fibrinolysis, lipid metabolism, and barrier integrity through modification of key regulatory proteins. By influencing phosphorylation-dependent signaling, enzymatic function, and protein-protein interactions, tyrosine nitration contributes to the connection between redox imbalance and progressive cellular and tissue dysfunction. This review summarizes current mechanistic insights into site-specific protein tyrosine nitration, highlights the emerging disease-associated nitroproteome, and discusses how advances in analytical and structural approaches are redefining nitration as a functional regulatory modification. Understanding the molecular determinants and consequences of tyrosine nitration may enable the development of targeted diagnostics and therapeutic strategies across diverse human diseases.