title: 1H-NMR studies of [Sar1]angiotensin II conformation by nuclear Overhauser effect spectroscopy in the rotating frame (ROESY): clustering of the aromatic rings in dimethylsulfoxide.
abstract: The conformational properties of the octapeptide [Sar1]ANG II in dimethylsulfoxide-d6 were investigated by rotating frame nuclear Overhauser effect spectroscopy (ROESY). Interresidue ROESY interactions were observed between Tyr ortho and Phe ring protons, between Phe ring and Pro C gamma protons, and also between His C alpha and Pro C delta protons. A weak connectivity was also observed between the Sar N-CH3 protons and a Tyr ortho proton. Intraresidue interactions between alpha and beta protons in Tyr, His and Phe indicated restricted rotation for the side-chains of the three aromatic residues. These findings suggest that [Sar1]ANG II takes up a folded conformation in DMSO in which the three aromatic rings form a cluster. Connectivities between the His C alpha proton and the two Pro C delta protons illustrated a preferred conformation for angiotensin II in DMSO in which the His-Pro bond exists as the trans isomer. The NMR spectroscopic evidence is consistent with the presence of a Tyr charge relay system in the biologically active conformation of angiotensin II and with the postulated role of the Tyr hydroxyl group in angiotensin II for receptor activation.
authors.affiliation: Department of Medical Biochemistry, University of Calgary, Alberta, Canada.
authors.forename: J M
authors.initials: JM
authors.lastname: Matsoukas
authors.forename: G
authors.initials: G
authors.lastname: Bigam
authors.forename: N
authors.initials: N
authors.lastname: Zhou
authors.forename: G J
authors.initials: GJ
authors.lastname: Moore
mesh_terms: D000595:Amino Acid Sequence; D000804:Angiotensin II / Q000031:analogs & derivatives* / Q000138:chemical synthesis; D055598:Chemical Phenomena; D002621:Chemistry; D004121:Dimethyl Sulfoxide; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008969:Molecular Sequence Data; D011083:Polycyclic Compounds; D011487:Protein Conformation
chemical_list: D011083:Polycyclic Compounds; D000804:Angiotensin II; C032651:angiotensin II, Sar(1)-Ile(5)-; D004121:Dimethyl Sulfoxide