Synthesis of endothelin-1 analogues, endothelin-3, and sarafotoxin S6b: structure-activity relationships.
Two disulfide analogues (types A and B) of endothelin-3 (ET-3; formerly, rat ET), sarafotoxin S6b, and apamin, were synthesized to determine their disulfide structures as in the case of endothelin-1 (ET-1; formerly human and porcine ET). The disulfide structures of ET-3 and sarafotoxin S6b were found to be identical with that of ET-1 (type A) but distinct from that of apamin (type B). The vasoconstricting activities of ET-3 and sarafotoxin S6b were about one-60th and one-third that of ET-1, respectively. Such different biological potencies between endothelins and sarafotoxin S6b could be largely attributed to the sequence heterogeneity at the N-terminal portion. ET-1 analogues were also synthesized to clarify the structure-activity relationships. The opening of any disulfide bond in the ET-1 molecule extremely decreased the activity, while oxidation of the Met residue did not alter it. Amidation of the terminal COOH group and extension of the Lys-Arg sequence to the N-terminus led to 16- and 540-fold decreases in activity, respectively. Removal of the C-terminal Trp residue resulted in complete loss of the activity. The other disulfide analogues (type B and C) of ET-1 showed markedly lower activity than the parent molecule (type A). These results indicated the importance of the whole molecule with the proper double cyclic structure for determining its active conformation.
Nakajima
K
K
Peptide Institute Inc., Protein Research Foundation, Osaka, Japan.
Kumagaye
S
S
Nishio
H
H
Kuroda
H
H
Watanabe
T X
TX
Kobayashi
Y
Y
Tamaoki
H
H
Kimura
T
T
Sakakibara
S
S
D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004220:Disulfides / Q000032:analysis; D016232:Endothelins; D066298:In Vitro Techniques; D008297:Male; D008969:Molecular Sequence Data; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D010455:Peptides / Q000138:chemical synthesis* / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013329:Structure-Activity Relationship; D014661:Vasoconstriction / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000138:chemical synthesis*; D014757:Viper Venoms / Q000138:chemical synthesis* / Q000494:pharmacology
D004220:Disulfides; D016232:Endothelins; D010455:Peptides; D014662:Vasoconstrictor Agents; D014757:Viper Venoms; C057354:sarafotoxins s6