1. Symbols and abbreviations are in accord with the recommendations of the IUPAC-IUB Commission on Nomenclature (J. Biol. Chem.1972,247, 977). Other abbreviations: Acxc, Cα,α-dialkylated α-amino acids (1-aminocycloalkane-1-carboxylic acid) (hexane,x= 6; pentane,x= 5; propanex= 3); Boc,tert-butoxycarbonyl; Boc2O, Boc-anhydride (di-tert-butyl dicarbonate); DCC, dicyclohexylcarbodiimide; DIPCDI, 1,3-diisopropylcarbodiimide; DMSO, dimethyl sulfoxide; DMF,N,N-dimethylformamide; EDC, ethyldicarbodiimide; Fmoc, (fluoren-9-ylmethoxy)carbonyl; HOBt, 1-hydroxybenzotriazole; IBCF, isobutyl chloroformate; OtBu,tert-butyl ester;1H-NMR, proton nuclear magnetic resonance spectrometry; Rink resin, 4-(2‘,4‘-dimethoxyphenyl)-Fmoc-aminomethylphenoxy-resin; TEA, triethylamine; TFA, trifluoroacetic acid; Z, benzyloxycarbonyl.
2. The opioid peptides of the amphibian skin
3. The toad, ugly and venomous, wears yet a precious jewel in his skin
4. Frog skin opioid peptides: a case for environmental mimicry.