GH1 and acromegaly: In other instance, pegvisomant (Somavert) prodrug conjugate is synthesized by covalent attachment of four to six Mw 5000 Da PEG units via NHS displacement to several lysine residues available on hGH antagonist B2036, as well as the N-terminal phenylalanine residue is used for acromegaly treatment [41–43].