Provided herein are modified amino acids comprising a tetrazine groups according to Formula I: polypeptides, antibodies, payloads and conjugates comprising these modified amino acid residues derived from the modified amino acids, and methods of producing the polypeptides, antibodies, payloads and conjugates comprising the modified amino acid residues. The polypeptides, antibodies, payloads and conjugates are useful in methods of treatment and prevention, methods of detection and methods of diagnosis.