Also known as (2S)-2-amino-3-[2-[(3S)-4-amino-4-oxo-3-(trimethylazaniumyl)butyl]-1H-imidazol-5-yl]propanoate
Diphthamide is a post-translationally modified histidine amino acid found in archaeal and eukaryotic elongation factor 2 (eEF-2).
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).