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I. 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

1990; Elsevier BV; Volume: 11; Issue: 2 Linguagem: Inglês

10.1016/0196-9781(90)90093-k

1873-5169

John Matsoukas, Glen Bigam, Ning Zhou, Graham J. Moore,

Protein Structure and Dynamics

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 Cγ protons, and also between His Cα and Pro Cδ protons. A weak connectivity was also observed between the Sar N-CH3 protons and a Tyr ortho proton. Intraresidue interactions between α and β 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 Cα proton and the two Pro Cδ 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.