NH2TrpProCysHomoArgGlyAspOSH2NHNNHSOOHO(S)OHNNHO(R)NHONH2S(R)HNO(S)NONH(S)HNONH2TrpProCysHomoArgGlyAspOSNH2HNNHSOHOO(S)ONHNHO(R)HNONH2S(R)NHO(S)NONH(S)HNO