title: A cyclic angiotensin antagonist: [1,8-cysteine]angiotensin II.
abstract: [Cys(S-acetamidomethyl)1,8]angiotensin II has been synthesized by the solid-phase method and purified by carboxymethylcellulose chromatography and reversed-phase HPLC. Treatment of this peptide with iodine gave the cyclic octapeptide [Cys1,8]angiotensin II, which was isolated by Sephadex G-25 chromatography and reversed-phase HPLC. Comparison of the circular dichroism spectra of the open-chain and cyclic peptides, respectively, demonstrated the existence of a disulfide bond with right-handed chirality in the cyclic peptide. In the isolated rat uterus assay, the open-chain peptide was found to be a potent antagonist of angiotensin II, having approximately 10% of the activity of [Sar1, Ile8]angiotensin II, and the cyclic peptide had about 10% of the antagonist potency of its open-chain synthetic precursor.
mesh_terms: D015059:1-Sarcosine-8-Isoleucine Angiotensin II / Q000494:pharmacology; D000804:Angiotensin II / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors* / Q000138:chemical synthesis / Q000494:pharmacology; D000818:Animals; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D005260:Female; D009682:Magnetic Resonance Spectroscopy; D051381:Rats; D011919:Rats, Inbred Strains; D014599:Uterus / Q000187:drug effects
chemical_list: D000804:Angiotensin II; C040564:angiotensin II, Cys(1,8)-; D015059:1-Sarcosine-8-Isoleucine Angiotensin II