ONH(S)OONH(S)NHNONH(S)NHONH(S)OHONH(S)OONH(R)NHONH(S)CH3CH3ONH(S)NHNHNH2ON(S)ONHNH2HNH2PyrHisTrpSerTyrD-TrpLeuArgProGlyCH3OAc