The present invention generally provides methods for the site-specific modification of peptides, polypeptides, and proteins, e.g., granulocyte macrophage colony-stimulating factor, human superoxide dismutase, annexin, leptin, antibodies and the like, cytokines and chemokines, at their N-termini and at sites at which unnatural aminoacids have been introduced along the protein framework. The modifications described herein can be used for the synthesis and application of the adducts in radio-labeling, molecular imaging and protein therapeutic applications, and the treatment of disorders such as rheumatoid arthritis, lupus erythematosus, psoriasis, multiple sclerosis, type-1 diabetes, Crohn's disease, and systemic sclerosis, Alzheimer disease, cancer, liver disease (e.g., alcoholic liver disease), and cachexia.
